You can wear a helmet while riding a bike, or you can not wear a helmet. There are arguments both ways; personally, I choose to wear one, but I understand that reasonable people choose not to, for reasons that are just as valid.
But lately I have seen something that makes zero sense to me: people who do not wear helmets, but still carry them around. And I have seen a lot of this lately. This choice seems to combine all of the disadvantages of wearing helmets (inconvenience, lack of style) with all of the disadvantages of not wearing helmets (reduced safety, judgment of passers by). Why?