And decades ago, people who ate "too much" saturated fat would have been penalized while people who replaced it with hydrogenated oils would have paid less while ultimately costing much more. All these years later, we now know that there was some pretty bad dietary advice/policy and the result could have been a whole lot worse if people were financially incentivized to change their diets.

This is a reasonable counterargument—though I'm not especially persuaded and it's a little bit of a straw man. Are you arguing that there's not enough evidence to substantiate an actionable belief that nicotine, alcohol & sugar correlate with significantly increased health costs? We already tax two of these on that premise—though not nearly the levels required to offset the costs they create.