I've never smoked pot, and don't plan on doing it even if it is legal. I hate watching my tax dollars go to waste, however.
If banning something works, it's hard to explain that I drank more in the 5 years before I was 21 than I have in the 10-years since I turned 21. And it's probably by a factor of 3 or 4.
Try that and you have heavily armed ATF thugs knocking in your door so fast it'll make your head spin!