I think it's one thing to overly minimize risk, it's another entirely to take stupid risks where the payoff doesn't match the risk. I play sports and get injured from time to time (I am still healing from an ankle injury sustained months ago), but it's worth it given how much fun I have - but I still bought shin guards because getting taken out for a week because of a bad kick just isn't worth it (that's more time I could be playing soccer, for instance). It's the same thinking with bike helmets. I want to be around to bike more.