Why is my brother such a jerk?

I am a 13 year old boy and I was wondering why my brother is such a dick. He talks to everyone like he’s better then them m even my parents. He’s only 19 for gods sake.

Why does he have to be such a dick all the time. He insults me almost every day and has never said a nice thing to me in my life. The only times he says sorry is when my parents make him, and that’s if they make him.

He is such a dick he was even voted biggest dick on the wrestling team. He is such a slob to. He just got back from college a couple weeks ago and now my life sucks. He is the main reason why I am depressed, not confident, and Anti-Social.