Most of them clearly have no idea what they’re protesting, they just want to protest.
Having marched/protested a few times over (the insanity of) Brexit, there’s something supremely gratifying, thrilling, and tribal about being part of a large like-minded crowd, as anyone who’s been to e.g. a big sporting event will know. It’s the protest itself that these TRAs enjoy, and the yelled/chanted misogyny is probably unwitting, mindless.
I’m certainly not excusing them, but protest can be exhilarating in itself, regardless of the cause.