I'm going to tell a story from my time in the fifth grade. There was a girl there, who was picked on, ignored, and generally disliked by everyone in the class.
Well, little me, a much more idealistic person than I am nowadays, thought, "This isn't right. Why is everybody being so mean to this poor girl?"
So, I decided to be nice to her. At the playground, I went up to her and tried to be friendly, tried to talk to her, tried to be nice. She basically told me to get bent and wanted to be left alone. Eventually I got the hint and left. The other kids made of fun of me for being nice to her, which was annoying but had no particular effect on my social standing. I was still, if not popular, reasonably well-liked by most of my classmates.
But I realized that day why nobody liked this girl or wanted to hang out with her. She was a bitch who turned her nose up at all attempts to befriend her.
After that I realized that people who are picked on and bullied by the majority of their peers, and not just one or two jerks, usually have a reason for it.