What actual evidence do you base this on? The South African government banned cigarette sale during the lockdowns. Evidence suggests that black market cigarette sales surged and failed to return to previous levels after the ban was lifted.
The economic concern with banning cigarettes is you will have similar numbers of people smoking, but now you've lost the tax revenue on sales while you still have to carry the healthcare costs. You also have increased costs related to policing and adjudicating the ban.