> Don’t be so lazy as to argue that a marathon runner makes comparable choices to an overweight layabout.
Marathon running is quite hard on joints, with an increased incidence of osteoarthritis. (There are also overweight marathoners, smoking marathoners, etc.)
> It’s just not true that people’s lifestyles are in aggregate equal.
Certainly, but there's an infinite number of combinations, and there's a serious risk to over-dividing the risk group. Pre-ACA, some folks found themselves shoved off into "high risk pools", which often made them functionally unable to access healthcare. Making folks uninsurable pushes them into more expensive (back to subsidizing!) emergency care, and causes them to delay treatment in ways that often exacerbate a treatable condition.
I suspect the folks here would riot if "sitting in a chair all day" wound up with a massive insurance penalty. Should eating meat come with an insurance penalty? Living in a smoggy city? Overindulging in beer?