[AaronBrown]

This may not be quite what you mean, but while people tend to overestimate the risk of doing something once, they tend to underestimate the risk of continuing to do it. For example, an extraordinary number of serious mountain climbers die climbing mountains. I recall one study giving a rate of 60% for serious Alpine climbers. Drivers with certain characteristics are also more likely than not to be killed while driving. It's not so bad for recreational Scuba divers and hobby pilots, but it's signficant.

Bungee jumping or skydiving is something you might do once, just for the thrill. But driving sports cars fast or climbing mountains takes too much training for one shot. If you decide on these activities, you're betting a good portion of your life.