Smokers already do, this on theory that they're courting a higher than average medical expense. So are the obese, but to my knowledge they haven't been targeted for higher premiums, in spite of all the comorbidities that require doctor's visits and medications. The difference, I'd say, is that smoking has been targeted by the left/progressives as a bad habit that anyone can break, whereas the same left/progressives have declared that the obese can't help it (read: victim), never mind that it's another 'bad habit that anyone can break'.