You could be right. Or it could be the exact opposite. Or something else. It doesn't matter. Fundamentally we do it to ourselves, because we're herd/pack/social animals. We shun anyone too different from the tribe, it's in our DNA. Because of that, we are highly evolved to fit in.

Yeah, we're self aware and all that, we have choices, but what we generally choose to do is identify with some group and hate opposing groups. It's what we do.

The chimpanzees are laughing at us.