> lung cancer treatments

A fairly large portion of lung cancer patients didn't "do it to themselves" (about 20% and rising).

It remains to be seen how vaping impacts lung cancer,

I don't like the idea of finding reasons to penalize people for predicable life decisions that lead to treatment needs. Insurance companies have a lot of resources to make those predictions and if unshackled they aren't afraid of using them. Making construction workers, miners, or truck drivers pay more (or be denied outright) for insurance because their job has negative health effects would be bad for society.