Does one wear one's helmet whist one is playing rugger? One is just concerned about the risk of head injuries from rugger, versus that of similar injuries from cycling.
One is never going to ask one that, considering that one does not wear a helmet oneself, while partaking in an activity much more dangerous than cycling, playing rugger or taking ecstasy.
I would certainly never wear a helmet again, if I could get my hands on this fetching little chapeau