Smoking could save money for society but it probably doesn't save money for individual insurers, who are much more worried about the shorter term. The private insurance you have when you're 30 isn't going to be paying for your nursing-home care when you're 90, but they are likely to end up paying for various smoking-related illnesses that kill you sooner.
We don't really have Health Insurance companies. Insurance is about risk management, and we have mandated health coverage. But, to your point, this is why real insurance companies manage their portfolios, aggregate. If they're losing money, it's not the responsibility of society to save them.
