Again I posed this question without any teaching. This is how my students responded.
I think that mom and dad didn't teach them the right way.
They lose their temper because they are angry.
They don't think before they act!
They think they're cool.
They show off.
I then added that bullies usually want attention. Bullies need understanding and care, while making good choices. They will need to learn how to control themselves while dealing with their anger.