Earlier quoted context omitted.
It's not really moral hazard, since that implies a rational choice is being made to make themselves sick because they know that they won't be bearing the financial costs. However, there are a plethora of non-financial costs to the diseases you've mentioned - up to and including death - so the moral hazard is mostly avoided. It's simply that some people make irrational, bad choices, and the incentives on the whole mak…
Moral hazard doesn't have to be rational, just a deliberate choice. Such as the choice to smoke, or over-eat. Yes, they can be addictive, but there are supports and cures for both, and involve willpower and sacrifice, but they're there. I say this as a fatarse who has lost 20Kg by eating less (The Horror!) and doesn't blame anyone except himself.
If the potential future cost of dying of lung cancer doesn't deter people from smoking, then the potential future cost of bankruptcy from paying for lung cancer treatment isn't going to, either.
It's about the mispricing of future risk rather than moral hazard. If you brought the cost up-front, by giving them health insurance but charging additional risk premiums to smokers, then you would likely find more rational decision-making around smoking.