If you don't mind me asking, how old are you?

Your situation sounds similar to mine. Sometimes, it isn't you. It's them. If that's true, then make friends with someone else.

You remind me a lot of myself in highschool, too. I was too cool for the nerds (in my own egotistical opinion at the time), and too nerdy for the cools (evidenced because they wouldn't let me in the group).

As a grown up, I am experiencing this again after a 20 year break! Weird. The only thing I have been able to figure out is, some people just aren't nice. If they truly are pushing you out because of your performance, or what you can give them, then they aren't really your friends. And they really don't want to be your friend. Why do you focus on them?

I think I mentioned it before, and I am going to try and take my own advice:

Make friends with someone that needs a friend more than you do. Who else gets picked on? Who else is not included in those peoples cool group? Find them, and there you will find your friends.

If that is beneath you, then you are no better than the group that is excluding you. Hard truth. Hard for me to listen to, too.