It's sad to think about how social relationships work and twist one's personality in order to "fit in". Sports, in general are a large part of our society and a catalyst to many social relationships, so to many people, there is an urge to join the bubbling pot of sports fandomonium to boost their social health. Is there a better way to be a part of every conversation than being perceived as a "fan" of the sports teams on top at a given moment? These types of people don't even care if they're involved in the social interaction for negative reasons (such as being a Tide fan in East TN). I watched a friend become a Gator fan years ago because he saw that he would be involved in more social interactions (though negative), thus fulfilling some sort of need in his soul that I will never understand.
Because the teams on top are the most talked about, there is a rush of people to claim to be a part of that team on top. The same goes for a team that is hated in a certain geographical area: to be the enemy means you matter. Unfortunately, I still see this friend engaged in conversations because of his UF apparel. Occasionally, there will be another Gator "fan" who will very loudly say, "go Gators!" Both of these individuals involved in the interaction will then bask in the negative attention received from the masses.