I drive on Sand Hill everyday to commute to work and often there are so many cyclists who are not wearing a helmet. Please wear a helmet! And if you are in scrubs or wearing a doctor's coat then please definitely wear a helmet. Or perhaps study the impact of a trauma accident of a bike, a skull and the road. Or if you are a parent and your children are wearing their helmets, why not set a good example and wear yours?
Spend the money, suffer through helmet hair but save your life.