A huge percentage of impulsive violence takes place under the influence of alcohol or other drugs. If you won't, don't be an idiot about drinking. Be with people you know and trust in places that are safe. Stay off the roads. Don't ever pressure others to drink or use.
People tend to be less horrified by violence when they are surrounded by death and violence.
Today, violence permeates our society. In the U.S., the average person sees 200,000 graphic violent acts on TV by the age of 18. And much of this violence involves guns. Guns have made us more efficient at killing. Five thousand years ago a drunken, isolated, hateful person could have tried to kill, but would have had no firearms to make it easy.