Making tobacco illegal would not decrease the number of people smoking it. Potheads should know better than that. If tobacco were illegal, it would just shift the whole industry to the black market, the prison population would explode from half the population being caught with illegal cigarettes, and teenagers would have an even easier time getting their hands on them (drug dealers don't ID...).

Smoking tobacco is a personal decision. I've never done it myself, but if other people feel like giving themselves cancer it's none of my business. If you decide to continue smoking and don't make any efforts to quit, you have no right to complain about how horrible it is, or to insist that nobody should be allowed to do what you're doing.