Role playing and they get into it deeply. Remember the Springfield Oregon high school shootings or was it Colorado. The two kids who lived in make believe world because theiy were punching bags for the school clowns and jocks. School did nothing about it. They had long trench coats they wore as sort of a uniform and one day swiped Daddy's guns and the role playing became real playing .Just no reset button. What was in common. the actual or perceived pressure some are put under by playgrund bullies. until something snaps and the digital refuge where they kill hundreds and millions becomes second nature.Definitely causation and the rest clicks into place. It doesn't take a large percentage. But starting with absent parents and the habit of treating our dogs better than our children who hype up on Saturday morning cartoon violence and the sugar that sponsors it. click click click it all falls into place.
The real anti social behaviour is ignored and even applauded. the message is violence solves everything and death is just another reset button.