This is something that John G. spoke to in his comment as well - that this is a deeply engrained concept that has only been reasonably challenged in the past 60 years, and only meaningfully in the past 15 or so. A lot of people don't know how to think in any other way, despite the scientific evidence and I'm sure it is disruptive because it's happening so fast - particularly since it seems to be a long time human predilection to reinforce who we are by accentuating who we are not.

I guess my compassion for that starts to wane when people are hurting others because they can't handle the disruption to their belief systems. The rising violence against trans women is a particularly visceral example.