If I'm sitting at home, avoiding skin cancer and excessive wear & tear, while you're running around ruining your joints and breathing car exhaust... ...why sho

If I'm sitting at home, avoiding skin cancer and excessive wear & tear, while you're running around ruining your joints and breathing car exhaust... ...why should I subsidise _your_ insurance? (really, America is so weird. Even in our rather terrible non-single-payer insurance system it would be illegal to base premiums on lifestyle. Insurance cost is decided by law, you may buy some extras, the end).