For those who seek the adrenaline rush of extreme sports, they ought to consider opportunities in the military. But admittedly not everyone is called to serve.
There is some crossover between extreme sports and military training. The Department of Army has instituted the Warrior Adventure Quest, which is a training tool to introduce soldiers to alternative activities to avoid aberrant activities after finishing a deployment. These adrenaline rush high adventure activities (like bungee jumping, rock climbing, mountain biking, paintball and whitewater rafting) are intended to help introduce coping activities to returning soldiers as they realize their new normal after deployment.
These civilian extreme sports somehow seem calm compared to what forward deployed troops do as they recreate in a combat zone.