Originally Posted by
jonwvara
..., his wife ("Anne") pleads with him to for God's sake wear his helmet.
Derek is a caring person who loves his wife and doesn't like to see her anxious and unhappy, so he wears the helmet. Why not? It doesn't matter in terms of safety, but it matters quite a lot in terms of his relationship with his wife. (Don't tell me, by the way, that he should convince his wife that she is wrong. As anyone who has visited this thread knows, it's impossible to change anyone's mind on the subject of helmets.)
As it happens, I have been in precisely this situation. I continued to go bare-headed. The woman in question would deeply resent your implication that she is too stupid to weigh the evidence and change her mind...
As for the rest of your stuff about tribes and self-image, I have already answered that. My decision not to wear a helmet is nothing to do with my image of myself, and everything to do with my image of cycling. It is not dangerous.