I liked what Yellow Bird said about teenagers and young 20's will probably outgrow being foolish. I think most of us can remember several times when we were young, where good luck or the grace of God saved us from an early grave. To describe those deaths that do happen to "defective genes" is a rush to punitive  judgment, which might be fun for the mean spirited, but lacks the balance that years ought to have given.
As far as when or if to wear my PFD, that was decided several years ago. I swim alright but not well with my clothes on, my real talent seems to be sinking. I was fooling around in my canoe and the next thing I know we do some sort of flip flop floop and I'm looking up through several feet of ugly dirty water thinking "this is awful stuff to be drowned in" and then the PFD pops me to the surface like a cork. It was love at first coughing choking breath of fresh air. The only time it's off me is when used as a pillow at night.
Best Wishes, Rob