football is really, really popular

I like football; probably too much sometimes. WHY?

Why do people get so into football? (NFL, NCAAF)
Is it a joy that we feel when we see a fellow species' member stretch a bit closer to the bounds of human performance? Is it just the rush of tribalism that gets us jumping and screaming at the tops of our lungs, even sometimes wiping away a tear after victory? I've heard or thought such theories before.

Could this be evidence perhaps that domestication is out-pacing evolution? As society imposes new requirements for civilization it squeezes the static individual, and it seems the more it squeezes the more we, as a nation, deeply unify with football. There simply isn't a switch with which you can turn human passion on and off--no bridle, other than time.