If you want to consult the wisdom of the crowd, you should at least try to go for a random sample, and not for a highly specific group of people like "People who like polls about bicycle helmets on a forum specialized in cycling". Furthermore is you look at the big picture, it's obvious that the great majority of cyclists ride without helmets. Even in Muhrica, one of the bastions of helmeteering only a large minority is into foam hats IIRC.