He was use to being hated because they'd rather knock/exclude since he wasn't a follower, or in check like everyone else. They'd never accept him because he had an option. He was tired of taking their crap in silence when he speaks up they make him out to be a villain for not being part of their scheme.
All terms and conditions got annoying if you asked them they would act like you're ruining their life or plotting against them. While they cant win alone so they gain numbers trying to turn everyone against you for not caring.
After showing interest and still kept out there was no reason to stay it wasn't worth it anymore. He moved on the more he stayed away the worse they got. If he made a mistake it would be held against him. If they made a error they'd expect you to turn a blind eye over all the double standards.