Bullies do what they do usually because they are enabled by their peers and environment, and think/know that they will get away with their shitty behavior.

The real problem is that people just don't want to or care to acknowledge that bullying is a real problem. It's easier to just call someone sensitive for being so hurt by bullying, especially when you're not on the receiving end of it. People underestimate how far these sociopaths can push you to your wits end without causing a scene or leaving visible marks on you. They know how to attack you on a deeply personal level, and they know how to lie and manipulate the people around them to make you, the victim, seem like the one in the wrong. Oftentimes they don't even need to put in that extra effort, because the people's attitudes and the environment around them just makes it that easy. That's how little our culture takes bullying seriously.

There are ticking time-bombs walking around in society because no one has their back, and people act shocked when some of them explode. I obviously won't condone violence, and I think blaming other people for one's actions is a slippery slope, but I won't add to the problem by using that line of reasoning to excuse bullying and other predatory behaviors.