It's the money factor where I draw the line. It's a kind of perverse selection that the best of these athletes in extreme sports are the ones who get paid to do it, though probably just enough to scrape out a living until they age out, or die.

I'm sure there's some obscure spelunker who died in a cave, unknown to anyone but their friends. It's the commercialization of risk for entertainment that makes it icky. At some point along that curve it's OK for a civilized society to just say no, to boxing, for example.