It feels like the strength and type of withdrawal symptoms for each substance plays a big role here. I've only ever been addicted to caffeine and cigarettes an

It feels like the strength and type of withdrawal symptoms for each substance plays a big role here. I've only ever been addicted to caffeine and cigarettes and while my withdrawal symptoms were terrible (almost-disabling headaches, anxiety, etc) I don't think they were ever so bad that it would make me violent. As opposed to people I knew that were addicted to cocaine and meth which would go absolutely crazy for their next fix. In the particular case of the person that was addicted to cocaine, money was not an issue and would still become violent when the fix was not available, so I don't think it's necessarily a function of price or access to it. Of course, my sample size is very small but given that I also know a ton of people that quit cigarettes and caffeine without becoming violent, I would say withdrawal symptoms are probably a strong component on how violent people get.