Confidence: I am as good as everyone else
Arrogance: I am better than everyone else
That's the difference between being bullied and not, in a nutshell.
Confidence. You got to have it. You can't let what others say of you affect you - and really not let it affect you, not pretend it doesn't while it eats you away inside.
Arrogance. I see many people here saying that bullies are cowards, weaklings, stupid, idiot and whatnot. Oh really? I find it very funny how we gather here and flame these people. But let me tell you, the moment you adopt an arrogant stance towards them, you 've dug your own grave.
You may fancy yourself a genius and them dumb, which is well and good. But apparently, they 're geniuses when it comes to human interactions whereas you are dumb as hell. You got to accept that people are different, not see them as inferior.
Even if you 're a loner and lack social skills, that's not a problem itself. Making effort to interact with people is appreciated. However, when you act like all you want is to be left alone, then you offend people. You send them the very clear signal that you think of yourself as better than them.
School is an environment where for good or for ill, people tend to pick on each other. You can't expect to be in such an environment and never be touched. That's asking for special treatment and you will get it, though not quite what you 'd like. What in fact makes most persons bullied such elusive targets is the way they react; whether it's to stay quiet and do nothing or to lash out in anger, or to call for some superior to settle the matter, it's unusual, which is what makes it so amusing to the bullies.
I understand that a bullied person would like to think he can somehow scare the bullies shitless so they don't approach him again, but that's out of touch with reality. To go on a rampage and beat them up, that's bad advice. Lose the damn arrogance, accept that among people you 'll have to tolerate things you don't like. And then, it won't be you.