It's a little different when you consider that the taxpayer funds everyones healthcare. Most people taking the side of requiring bicycle helmet laws are probably thinking "I don't want my taxes going towards looking after some numpty who was too stubborn to wear a helmet and crashed".
People arguing this position are assuming that requiring helmets will decrease the risk of injury, which I am well aware there is conflicting evidence around.
I guess but I don't think it's as rational as that.
I mean you generally don't see people arguing compulsory helmets for car passengers. Even though the number of people requiring medical treatment head injuries caused by cars is orders of magnitude higher than it is for cyclists.
People arguing this position are assuming that requiring helmets will decrease the risk of injury, which I am well aware there is conflicting evidence around.