If the chute fails to open you're dead. If you pass out or have a heart attack on your way down and can't pull the thingy to activate the parachute, you're dead. Also in mountain climbing. One miscalculation and it could cost your life. Or those extreme sports where you can get paralyzed if you fall wrong or even die. Golf and tennis and basketball are pretty safe. Ice Hockey can be deadly of get elbowed or high-sticked in the wrong place and so can football if you get enough concussions. What causes some folks to be drawn to those activities that carry with them the potential for great harm/damage/danger/death? Living life on the edge?
Years ago, some friends from work and I went out I did a tandem skydive. It just seemed like a fun thing to do and I didn't give any thought to the "what ifs." It was an incredible experience, but once was sufficient. We went up in a hot air balloon in Taos which was a lot of fun, too and my last experience with "extreme" sports was white water rafting in Pennsylvania. That was the most dangerous of them all since the raft got hung up on a boulder and went almost vertical and we had two kids in the raft with us who we had to make sure didn't fall out of the raft. Suffice it to say, we managed to get ourselves safely to shore, but we were soaking wet and exhausted by that time. I am now the proverbial couch potato. :)