Self-righteous helmet naggers are a much more prevalent danger to cyclists than physical injuries.  There’s little evidence my helmet would increase my physical safety in case of an accident (there’s as much evidence for the opposite, in fact), but it does protect my social safety. If I suffered an accident, I’d need the support of my friends and family, and they threaten to withhold this if I don’t wear a helmet.  So I do. And then I make cartoons complaining about it.