Have any of your non hat wearing friends lost their hair? Sometime we see something or read something and it is easy in our experience to cherry pick that part out. I did not see any mention of the hair status of any non hat wearing friends in your post.

We read it, it settled in our memory, and we remember that Bill and Bob both wore hats all the time and are now bald, we forget that Joe and John who did not wear hats are also bald, but they did not fit the memory of the book we read.