[This is a roundabout answer to Silverblood's question about a fan's psychology, and I hope a good supplement to everything being discussed in the comments there.]

Sport as Art

To lead off this theory, I would like to say that I am basing it on the idea that sport/sports/sporting events qualify as art and that its practitioners qualify as artists.  I understand that this may be a debatable point with many of you, and I would be happy to supply my reasoning, but not in this particular post.  But ask and ye shall receive.

The Purpose of Sport (Art)

Silverblood gave an excellent characterization of a fan's investment  in their team.  Like any artform, the spectacle of the team is of passionately intense importance and profoundly personal concern to those who follow it, yet as she noted, the phenomenon reamins shrouded in mystery with little known about its function in human life or its tremendous psychological power.  And the phenomenon is hardly localized:  sport, and thus fans, have existed in every known civilization across every era of man's existence.

One thing that is often regarded as a distinguishing characteristic of any form of art, including sport, is that it serves no practical, material end, but instead is an end in itself.  There is no purpose to the event except contemplation of the event.   This leads to it and most forms of entertainment/art like movies, video games etc. being considered "leisure" which is often interpreted, even by those who really enjoy the activity, as being "wasteful" or unnecessary.  Anyone who suffers from fandom as Silverblood has described knows that "unnecessary" couldn't be farther from the truth.  If it was so "unneccessary" why would we struggle with it instead of abandoning it?

The reason is that it DOES serve a "practical" human need.  The difference is that it isn't a "material" need, but a need of our consciousness.

Our survival is dependent on several things.  Just as we must nourish our bodies with food, and nourish our minds with knowledge, so too we must nourish our souls with fuel as well.  That fuel is provided by art, and when you are following your team, you are trying to stock up on that fuel.

The way that fuel comes to be has to do with the nature of a human consciousness(soul).  The nature of a body demands that only certain things qualify as food (wheat is good, concrete is bad).  The nature of the mind means that only certain things qualify as knowledge (facts are good, contradictions are bad).  The need for art comes from the fact that the link between our body and mind has a certain nature, just like the body and mind themselves, and thus the link's preservation requires "sustenance" with certain qualities.  (The qualities it requires are "essential" vs. "random" and "important" vs. "inconsequential".  We may look at the qualities in depth a little later.)

The nature of the link itself could use some explanation, but I won't get too in depth.  Basically our bodies work a certain way (physical) and our minds work a certain way (thought) and the two things need a link that joins the two elements together.  That link is served by the conceptual cognitive faculty (consciousness) of a human being.   It links the physical world to our mental world not by isolated percepts (individual things we see, without any sort of context) but by abstractions, or concepts. (A concept is a mental integration of two or more units which are isolated by a process of abstraction and united again by a specific defintion.  By organizing our percepts (what we see, hear, etc.) into concepts (like hoosierteacher) and wider concepts (all teachers) and still wider concepts (people, all of whom could be teachers) a person can grasp and retain, identify and integrate an unlimited amount of knowledge, knowledge that extends beyond the immediate concretes at any given, immediate moment.)

In a nutshell, art, and sport as an art, is nourishement for the soul.

The Method of Sport (Art)

While conceptualization, the process of going from the physical world to knowledge, is an essential aspect of the link between mind and body, it is also a largely automatic aspect.  Even babies conceptualize.  There are some things you can do to enhance or degrade the quaity of your conceptual faculty, but from there the process continues on its own.  Of much more interest to a sports fan is how you go from knowledge back to the physical world.

Basically this consists of knowing something (holding a concept) and doing/creating it.  Among the concepts you acquire will be a whole class that pertains specifically to actions you can do.  By properly learning to abstract those concepts into even even higher concepts you will gain a class of actions that are powerful tools for not only deciding which actions you could do, but which actions you should do as well.  These concepts are commonly referred to as virtues, and include honesty, independence, etc.  Discovering and defining these concepts is what the science of Ethics is for.  

Virtues by definition are very unique actions.  They are actions which are required for survival (via the following formula:  virtues are actions that lead to the acquiring or keeping of values; values are things required for your survival).  Many simple and easy to understand virtues, including defending yourself against an initiation of force, earning your keep or eating to sustain yourself.  But there are a whole host of virtues that are much harder for people to pin down consistently without giving it a lot of thought in order to automatize the process.  These include ideas like justice, productiveness, etc.  These concepts tend to be very context dependent, and thus require that a person have a lot of info before a decision can be made and action can be taken.

Now we are starting to get closer to our goal.  It should be becoming clear that as these concepts add up from a literally infinite supply of concretes (actual units in existence) that whatever system you are using to organize them will become increasingly complex.  Unit reduction (creating higher concepts out of lower ones) allows us to keep up, but every human being has their limits, established by a combination of genetics and effort.  The more complex the system becomes, the more time is required to properly integrate new, wider concepts (though it should be noted that via language, if one person discovers a new concept, they can easily make it available to others, like Guru calling all the minutea of the 2008 season "The Quest".  It will still require effort from everyone to understand, but much less effort than everyone figuring it out for themselves.)  Many people will balk at the added effort and subsist fairly well on the knowledge they have acquired up to that point.  But a few will push the boundaries and keep pushing the whole thing forward.  Scientists drive forward the physical concepts, philosophers drive forward the intellectual concepts.  But who drives forward the concepts that stand for virtue, the concepts of the mind-body link?

The artists.

Consider the complexity of the philosophical system you employ for yourself (don't worry, you have one, even if it consists of saying you don't.  Integrating your concepts isn't something you have a choice about.  The only choice you have is in HOW you integrate them.)  While the entry point into the system for most people is ethics (represented by the question "Should I or shouldn't I?" i.e. what is right and wrong?) the concepts themselves are part of the discipline of metaphysics, the core and center of philosophy, from which all other branches leaf out from.  Metaphysics--the science of dealing with the fundamental nature of things--involve's not only your widest abstractions, but EVERY abstraction that you have ever made and ever will make.  It includes every concrete you have ever perceived and such a vast sum of knowledge and such a long chain of concepts that no one could ever hold it all in their conscious awareness at one time.  Yet it is exactly that sum that you need to guide you in your everyday life, not once or twice a day, but for every choice, decision or action you make.

Remember how I said that the qualities of concern for the mind-body link were "essential" and "important"?  Well, that is what the artist's concern is.  He takes that vast sum and, according to his selective judgment, isolates and integrates what he feels to be the most "essential" components, the most "important" concepts.  An artist may choose anything, and any medium within which to represent it.  Their job, upon choosing the element and the medium is to create a perceptual concrete, something real that essentializes what they wish to show, thus summoning the power of the concept--and the chain of concepts leading up to it--into full, conscious focus.  Where there was once a vast collection of concepts, there is now a single painting, sculpture or aria, which speaks for the artist, and speaks to the viewer.  What it says is almost too much to be put into words.

There are as many mediums for art as there are human virtues.  Every medium has at its core an aspect that is essential to it, that can be produced in no other way.  A dance can never capture the instantaneous moment captured in a  painting.  A painting can never show the inner thoughts of a subject the way that literature can.  Among the arts a need existed to show specifically the physical relationship between a human and existence.

Enter the athlete.

I don't know specifically what role sports occupies in art, but I am working to figure it out.  I have noted that every sport is physical in nature, some requiring more from the mind than others, while all that I know of involve competition.  I suspect that the concepts being pushed forward are political concepts revolving around men's proper relationship to eachother, in a political sense, but I'm not 100% sure.  It will be a good topic for later, I'm sure.

The Fan

Finally, we get to what we came here for.  I have tried to establish an argument that posits sports as a fundamental requirement of man's nature, but not as an activity in itself.  While athlete's no doubt enjoy the perks of being faster and stronger than most, that is no different from a painter enjoying better hand eye coordination than most people.  The true value of sports is in the contemplation of them.  Athlete's should expect to be well rewarded in their striving, and the nature of compensatory competition may have come about specifically as a way of engaging people into becoming athletes as opposed to firefighters or something. 

It may seem that individual sports attract fans on a much more rational basis than team sports, but I don't believe this is true.  First off, one must recognize that your reasons for favoring a team are vastly different for your reasons for favoring a sport.   In fact, reasons for liking golf or weightlifting or baseball are all remarkably rational and similar, usually involving some combination of physical attributes essentialized by that particular sport, which a person finds particularly admirable.  Based on this, one tends to admire the athlete/artists that best epitomize those admirable virtues. 

For selecting a team to root for, the reasons for establishing your fandom are almost always reasonable in a  reasonable person.  Liking your father's team makes a ton of sense unless you dislike your father.  Liking the home team makes a ton of sense unless you dislike your home.  Maintaining your fandom is another thing entirely.  You won't stay a fan of a team that does not reflect your core values (as embodied in the persons and play of the players/coaches).  Now, this doesn't mean that when they do something you don't like that the proper course of action is to abandon them.  Mistakes are a part of life, you learn and move on.  You don't kill yourself for choosing the wrong flavor of ice cream, and you don't abandon the Broncos because they had a bad draft.  But if the Broncos, for example, from the top down, decided that the future of football was FAT, fat WRs, fat QBs, fat cheerleaders, well, you would at the very least go into an extended hibernation until that bout of crazy had passed.  Fans of the NFL tend to understand that elite physical specimens are at the heart of success in the game, and probably feel that in life, such physical acuity would be a great boon as well.  If your team abandoned the fundamental principle, the essential aspect of football that reflects your fanhood, you would feel nothing in abandoning them.  You really wouldn't.  It would be immoral if you did try to feel bad about it, since you would be contradicting your own favored principles in favor of someone else's for no reason other than they want you to. (If that.)

While interesting, the above was treated in depth in the great comments of several posters on Silverblood's thread.  What is more engaging is the deep psychological reaction we have from winning and losing.  If I haven't described anything else here, I hope that I have successfully established that appreciation of a sporting event and its participants is a deeply held belief on the part of most viewers, as deep, in fact, as that person is themselves. 

Mnay sports fans become ever more fanatical as the years pass, making up for decreasing vigor with increasing surety and knowledge, a form of vigor in themselves.  What they are a fan of increases day by day, from being a winner, to favoring different players, to favoring types of schemes, to favoring whole-team philosophies for long term success.  The grander the scope of your fandom, the more you will be able to put up with.  (I would like to note that you do not necessarily have to hold a wide scope consciously.  It is possible to have that same depth of understanding without all the fancy words and without talking about it.  But identifying it, as so many here at MHR have taken the time to do, is a crucial first step in obtaining the confidence in one's ability to protect that knowledge from sabotage, say by a well-meaning, but ignorant friend who tries to tell you "how it is" with your favorite team.)

One last thing I would like to mention is the physiological connection, i.e the literal pain or elation that you might feel when your team wins and loses (or worse).  The reason is that your philosophical system, either implicitly or explicitly contains an ethical code.  That code contains not only our estimation of yourself (what actions you need to do to survive) but your estimation of existence itself (whether survival is a worthwhile goal or not).  The two components together add up to your self-esteem, an absolutely CRITICAL aspect of your life as a happy human being.  (I can't stress that point enough.  CRITICAL.)  When you put the full weight of your values behind a team, and depend on that team to succeed, what you are feeling is the emotional/physiological response of having your self-esteem questioned, or outright denied in some cases if they fail.  You will notice it is a very similar feeling to when you were younger and that cute boy or girl (hopefully you could tell) told you that they didn't like you and wouldn't go out with you.  It sucked then and it sucks now.  As for the other side of that coin, when your team succeeds?  Well, I'll leave you with this thought:

I mentioned earlier that artists may choose any medium and any subject with which to create their vision, including the methods of organized football.  The result is as profound a statement about themselves as about anything else.  Their souls are bared. 

And yours is too, when you respond to their work.