I bullied other people in school, but some I didn't bully as I knew that I couldn't handle them without my friends. There was a giant in my class, who participated in national championship of freestyle wrestling. I would never have thought of bullying him, he'd kick my ass unless I come with my friends.
As someone who bullied many people, among them also skinny and the weak, I can say, that you don't carry these habits with you if you're grown-up.
When you're grown-up things change as hierarchies or wage-structures define if you are a potential target to get bullied. Than there's police, courts and all that type.