Your original argument wasn’t about minimum voting age; you claimed the law would backfire due to the current generation.
The point is to eliminate cigarettes over a long time period and many generations, so I don’t see how it would backfire. How would there be more smokers in 2093 if the minimum age to buy cigarettes is 85?
If you want to change your argument, that’s fine, but my comment was in response to your original argument.