Why is this guy in my tutor such a ****?

This boy in my tutor (form) is a complete douche bag. He's 13, smokes weed, isn't a virgin, has been arrested before, taken about 3 months off school, got his cousin sent to prison for 3 years because he made him take the blame for getting caught with weed, and he's a complete chav. He doesn't do any work in school, and just enjoys making my life a misery. I have naturally dark hair and pale skin, and because of that and the fact I like rock music, he calls me a goth. He's a ******* chav and he doesn't even know what a goth is. If I say something to him when he's insulting someone else he says something like "**** off goth, I wasn't talking to you". He has like 3 friends and he thinks he's really hard. He's a complete **** and a bully, but why do you think he bullies me? He also calls my friend a tramp all the time, and makes fun of a couple of boys in my class. Why is he like this?