The people that don't wear them all the time, why not? Its not hurting you at all. 99 times out of 100 it will save your life. Sure there is that 1 time where it will hurt you more than help you, but I'd take that chance. It takes 2 seconds to buckle up. The only time I don't wear mine is if I'm in my driveway and not going onto the street at all(like just rearranging cars). Even going 15-25 mph it can save you from more injuries.