They don’t “want to be criminals”, though, they want to make money selling pot. Right now that is a criminal activity, but they would much prefer it to be legal. If it’s legal they’re not looking to find some new criminal activity to participate in. You are assuming here that selling pot is a “vice”, but it’s simply a criminal activity supplying a “vice”; selling pot isn’t an activity that people seek out for a thrill or get addicted to.
Actually, regulation on cigarettes and alcohol HAVE lowered youth use of these drugs. Youth use of alcohol and tobacco are far lower in the U.S., where access is restricted by age, than in places like Russia where it’s not. Kids can still get a hold of it, but it’s much harder when it’s legal and regulated.
The point is that it won’t be profitable to compete with legal growers. These laws were written specifically to undercut the black market, and have scaling tax levels and fees to adjust down if needed to push out the black-market dealers. The cost of illegal pot will always be higher than legal pot, all things being equal, because of the added cost of smuggling, bribes, guns, ect. The mafia didn’t keep a big hand in the liquor market after Prohibition ended precisely because it wasn’t worth it. They moved into other markets, but they’ve never come close to replacing the revenue they made from liquor, and the U.S. mafia has declined significantly because of it, as did bootleggers.
This is just one blow against drug cartels, but it is potentially a very serious blow. However, price it higher than today’s street prices and this will only keep the cartels coming across the border. Either way, the cartels are a criminal element meeting a demand.
You’ve not yet responded to the fact that the side-effects you listed are the same as those of alcohol, yet alcohol use is moral. I wouldn’t go so far as to say that smoking pot gives honor to God, at least in most cases, though neither does having a beer when watching a football game. You can give thanks to God when you have a drink, or a smoke, however.
Peace and God bless!