It is, after all, THEIR head.
Medicare should not be used as a bludgeon to force societal norms on people.
Its their head but our medical system that bears the brunt if they're too stupid to protect themselves and require more extensive medicinal treatment when they crash. I'm still surprised by the lack of helmet laws in various US states: I'm surprised the life/medical insurance companies don't have language to the effect that "if you don't use PPE, you're on your own".