I was a smart student, in school, and I wasn't really bullied much (mainly because I went to a pretty small school). Though, I will admit that I, personally, /was/ the bully. I picked on a lot of people and relentlessly pushed and pushed them really far. Why? Because it made me feel better about myself. Call it an inferiority complex, if you will. I do, anyway.
Long story short, if anything, underneath it all I felt as though if I didn't pick on everyone around me, then I would become the target, instead. I'd rather be the asshole, than be the one picked on, personally.