How come my brother is so mean?

My brother who is 18, (7 years older than I am) gets whatever he wants. An iPad, a car, a laptop, money, everything. And every time someone wants a favor from him who isn't me, he'll happily oblige. But whenever I ask him for something I'll get the same answer: "do it yourself. You have two legs that work!" But whenever he asks for a favor, he expects me to do it no matter what. And he hits me and puts me down and my parents let him. Is it my fault?