One of the reasons I think some men react so badly to Caitlyn is because of Bruce's athletic achievements. Human beings are hierarchical - we want to know our place in the pecking order, for the most part. Men who have athletic prowess are awarded very high status in the eyes of others. I observed this with my roommate, who is a former pro athlete. She had a bunch of friends who were her friends because she was a kickass athlete at one time.
Once she came out to them, suddenly they had a problem. The person who they had, all this time, brown-nosed because of their athletic prowess was now telling them "I'm a woman." This is intolerable to the male ego. Even relatively crap former high-school athletes will make fun of my roommate if she just mentions she used to play sports. They just assume, as men, they were superior to her in whatever trifling little endeavor she might have done. In point of fact, unless you are a particularly elite athlete, she was better at sports than you. Doesn't matter what you did, probably. She was exceptionally gifted. This has brought down a bunch of hate on her from some former friends during her transition.
In essence, they got beaten by a girl, and it bothers them. They don't know where they fit in the hierarchy anymore! Are they really men enough? It's one thing if a bigger man bests them - but a woman!?!? Inconceivable!
So look, Caitlyn was arguably the best athlete on planet earth at one time. Didn't matter who you were - she was a better athlete than you.
And we now know, she's a woman.
That massive hissing sound you started hearing in the background after her interview with Diane Sawyer is the sound of hundreds of millions of male egos deflating, and they are not happy about it.
