Kinda like bungee jumping. It's fun as hell. We love the pleasure of it (those who do it). But if something goes wrong we die. But those who do these things realize that they are just a heartbeat away from total oblivion. I think it has to do with our ability to reason. Knowing what is right and wrong and the entire thought process of humans. Monkeys don't know that swinging on vines is dangerous, if we do it, we are thinking that if we slip, we break our neck. It has alot to do with reasoning and perhaps a little insanity to go along with it.