it happens, kind of like when the parents beat up the MC so the MC does the same to someone who they envy because that person seems to live a happy life. I mean it's happened to me but my life's not happy, I just like to smile.
It happens all the time though. There are several reasons why. Either they are trying to empower themselves from previous situation by doing the exact same thing to others or trying to understand what it feels to be on the other side to answer why they were bullied/abused etc. There may be many reasons more. It takes psychological maturity or healing (whatever you call it) to reach a mindset of empathy for those abused/bullied/victims.
Ugh, i don't like the uke, he knows how bullied feels like then starts bullying others because of jealousy?? I'm out.