It's not the games and media, it's the entire system of school, family, and society. We try to make everyone fit in, no kid will fail, at home no responsibility. So there is no achievement and drive, just floating along until something doesn't go your way. Then what? No idea what to do because you have never been challenged before. Eventually they may think, hey if I just get rid of this guy it won't be a problem anymore. So they steal someone's gun and are off.
Gamers, real gamers. People who play video games a significant amount of time do not play violent games because they are violent. They play them because the art, storytelling, universe, mythology in the game world, and characters draw them into the fantasy world. I assure you that no video game you can find whatsoever is going to make a person able to discern reality from the fictional game world, a violent person. I will say that a person who is prone to violent acting out and instability will be drawn to the shooter games and probably not interested in the adventure games and slow paced games that make you think and strategize.