I wear a helmet when I ride my motorcycle. Why? Because it's the law? No, I value my life, and believe I am much safer with it on, then off. But when I ride my bicycle, I don't wear a helmet. Why? Because I'm traveling at a slower speed, and well, I don't have to, according to the law.
I have been on many accidents involving bicycles, and though some bicyclists have been badly injured, I have not been aware of any who have died. They may have, but I am not aware of it.
One bicyclist wearing a helmet, took her eyes off where she was headed, and rear-ended a parked car. She flew off her bike, and went through the back window of the car. Picture a car with two legs sticking out of it's rear window, and you can figure out how much she was injured. Did you imagine a bloody mess? Well, she only had a few cuts and scratches. This is a good example of how a helmet protects you. Of course we took her to the hospital so she could be checked for internal injuries, but I believe she was okay.
I have also been on two skateboarders who fell and hit their heads. Neither were wearing a helmet. One was going too fast down a hill and hit his head on the street. The other got hit by a car when she crossed a busy intersection, and her head hit the car's windshield.
Both died. The first a few days after, the last on the way to the hospital. Both were over 20 and under 30 years old. Do I think they would have survived if they wore helmets? Yes, especially the first one.
Do I think you and I should wear a helmet whenever we do anything where it's possible to hit your head on a hard surface? (Like cycling, skateboarding, rollerblading, skating, skiing, snowboarding, etc.) Yes, we should.
Don't be stubborn, because no one is really hard headed.