> If the CCP decided to ban smoking, it would be a violation of people's rights. But it would also be a net benefit to almost everyone, and to society
I think you are conflating “banning” with “convincing people to stop”; these are not the same. The PRC has banned lots of things without actually stopping them, and lots of countries have banned lots of addictive drugs without stopping their use, and with a whole lot of social harms resulting from the attempts to enforce the bans.
> health care costs would go down
Health care outcomes would no doubt improve if smoking was reduced by a ban, but healthcare costs would probably go up. IIRC, most studies have shown that reducing smoking increases lifetime healthcare costs (because, simplifying, people spend more time dealing with treatable problems instead of dead from incurable lung cancer.)