Some of the most intolerant people are also marginalized.
The truth is that some people look at identity as a tribe. Anyone not in the tribe, even if by sticking out a little is an enemy.
Some abused people go on and become abusers themselves.
It is common that those people then justify hatred, abuse and harassment by calling it self-defense.
Being marginalized and being a kind person are two different things. You have to work hard for the latter.