Why did Buddy hate Arnie so much?

Well, why does any kid/teen in schools hate other kids or target a particular person. I think Buddy targeted Arnie because it made Buddy forget about the loser he really was. Arnie had loving (but extremely overprotective) parents while Buddy had probably repeated a few grades and had a dismal home life.

I take it you have never seen bullying or been bullied in school?

Christine is one rare kind of movies. Its a teenage life representation that doesn't make me sick when watching. I think its largely because of John Carpenter's directing. Thanks, John.

Like EB says, bullies like to target the weak and vunerable.

Law of the jungle. Buddy was tough, Arnie wasn't.

But Arnie sure showed that shitter, didn't he?

Buddy was upset that even though he was a dead ringer for 70s Travolta, he was pissed that the Travolta got cast in Welcome Back Kotter. So he took it out on Arnie, who survived a Great White Shark attack in Amity the previous year.

Because Arnie was a nerd and made Buddy feel like he had Power over him