Depending on your age, it's likely that you can remember riding a bike often without the thought of ever wearing a helmet. In fact, I don't even recall if they had helmets when I was young! Over the years we have become very acquainted with the real dangers of riding a bike without a helmet and in many jurisdictions it's a law for anyone under 18 to wear one when riding a bike. This is for very good reason as studies have shown that wearing a helmet can reduce the risk of a head injury if you happen to get into an accident on a bicycle.
It's such a simple thing, to wear a bike helmet, but often many people just don't think to strap on a helmet. While you may think that you are a competent rider and that you won't get into an accident, the truth is, if you ride often you do stand the chance of getting into an accident at some point in time.
The implications of getting in an accident without a helmet on are not good. Many people have suffered serious brain damage from not wearing one. Even if you feel confident riding a bike, what if you were hit from behind or you hit a bump that you did not see? Something like this could cause you to lose balance and fall to the ground. If your head were to hit the pavement without protection, there's a good chance that you could suffer brain damage. This injury could be a concussion or something more severe that limits your ability to walk, talk and live in independence. It seems silly to think that just because bike helmets don't always look "cool" that people would risk losing their job and their freedom, just to ride with the wind blowing through their hair.