if you wanna know how extremists are made just consider the following

loner seeks female attention
loner rejected and deemed a creeper or whatever
loner sadposts and/or asks how to do better
everyone shits on loner for not gitting gud
loner repeats the process until seasoned
soul chips away at endless rejection
someone from an extremist faction eventually invites them over
they're rewarded with attention
they adapt their personality to maximize praise in the only people who will give them any

congratulations. that's one of the ways monsters are made.