Tribalism.

Indeed. But this is what I have increasingly come to appreciate about it.

People are tribal inherently. Sports is a way that tribalism can be expressed in less serious or dangerous ways, and most people can shake hands at the end of a game and be cool.

I used to think that humanity would be better off without any kind of tribalism, but the older I've gotten, the more I think it's completely unavoidable. So given that, maybe we can sublimate some of the harm by redirecting tribalism to stuff that isn't all that important.