Nothing. The problem starts when they kill other people doing it, which is unfortunately very common with automotive collisions. It's like when someone gets in

Nothing. The problem starts when they kill other people doing it, which is unfortunately very common with automotive collisions. It's like when someone gets in my car, sits behind me and says they won't put a seatbelt on, they are fine with taking the risk - to which my reply is that it's fine, but I'm not fine with taking that risk, because in a collision your limp body will go directly through my seat and kill me, even though I have my seatbelt on. So yes, kill yourself if you wish, but don't take others with you.