So I drink more pop than I should. Why should I have to pay more for my healthcare than my buddy who had a habit of timing running green lights as soon as they turned green. That isn't illegal, either, yet it's very risky behavior. It didn't work out for him just one time, and he nearly died. Why should taxpayers have to pay for him?

The answer is because the vast majority of us engage in risky behavior, or just have the bad taste of passing on our poor genetics to the next generation, and the social cost for penalizing people for not agreeing with societal norms are too high. This includes drug use, even legal ones like alcohol. Sure, don't spend limited resources such as donated livers on people who aren't willing to make the lifestyle changes required to make it worthwhile, because someone else will probably have to die for that to happen. But if we could make new livers and the price was reasonable, I wouldn't even be against that.