It's not that Rowling's belief is all that outlandish. In fact she's probably more pro-trans than the median Westerner if we're being honest.
The problem is that she is OBSESSED with the issue and her own victimization complex about it. Like, she Tweets about it multiple times a week. This whole "controversy" could have died out years ago -plenty of celebrities have expressed worse opinions before without becoming pariahs because they let it go - but she for whatever perverse reason won't let it.
Kinda like Dave Chapelle.
I think she's much more annoying about it than Dave Chapelle. In his last Netflix special, Dave made like 1 or 2 jokes about trans people over the whole hour+, which is a good bit less than he made about [insert race here] or [insert religion here].
I would have no qualms about going to see Dave Chapelle live if he came to my city, but I just wouldn't have any interest in seeing JK Rowling. Not because I think she's eeeeevil and needs to die or whatever she pretends that her critics say about her outside of random anonymous social media accounts, but because I just don't want to feed her victimization grift.