My personal take on bullies (and many others that become violent or dangerous) is a lack of coping skills. The ability to cope with life used to be taught to us as kids, it was taught right along with the ABC's and birds and bees.
Now, we don't teach coping. We teach "Take this pill if you have a problem, but if no one gives you a pill, then you don't have a problem." We no longer teach kids that they will have to deal with people they don't like, or that they have to be nice for no reason and with no gain. We don't teach them to cope with life, and that has led to having three classes of kids: zombies on meds because they had a problem, kids that had no diagnosis, just a marked lack of coping skills that were ignored until they became aggressive as bullies, and victims with a lack of coping skills that is ignored until they kill themselves because of something that they should have been taught to cope with.
Great for the future generations: We'll have a world of bullies (which we have always had), drugged out zombies (which are becoming much more common), and suicide survivors (which would be happening less if parents were teaching their kids how to cope, even when the bullies parent's don't).
Unlike most people, and I know it will get me slammed, I am of the belief that when a child kills themselves due to bullying, there are a lot of people to blame: The bully, and whoever was responsible for their upbringing, and whoever was responsible for the victim's upbringing. It's on both sides, in my mind, because if a parent is watching a child, and removes the opportunities for bullying, or teaches the child how to cope with mean hateful people, (as they will be doing every day for the rest of their life) then the child's life is no longer at risk. Bullies are not new, the over-the-top reactions of the victims are. It's time for parents to start protecting their kids from themselves, not just demanding that the schools and the government do it for them.
JMO. Unless there's a link, I can't prove it.