Why would parents raise their child to be a bully?

Instead of teaching children conflict resolution skills, they teach them to strike back in a physical manner. Some parents just don't know any better themselves but what's worst is, they refuse to learn. They know better then the experts of course. You also have the, it's how I was raised defense. Bottom line is that the parents are idiots and raise their children in their likeness and they're to stupid to change the behavioral patterns.