I was really glad that I was wearing a helmet on a bike trail (no cars) when I had a bad crash. I have no idea how bad my head would have been damaged if I did not have a helmet on, but it took two shoulder surgeries and almost three years of physical therapy for me to get to not-quite normal, but mostly functional. Thus, it is very possible that I would have had a very serious head injury too.

Thus, I think there is a certain amount of Darwin's theory to who wears helmets and who does not.

My helmet hit the ground hard enough that my mirror that was attached to the helmet was busted in two different places.