Except that hasn't really happened anywhere else weed has been legalized, so not sure why you'd think that when there's demonstrable evidence to the contrary.
Hey smartass Germans have been getting faded for a while, it's been de facto decriminalized for years (aside from in B*vria). Go to any major German city in the past decade or two and you'd smell it as fast as in Cali. If you spent a day in Berlin you'd smell it on the clock lmao
I don't smoke pot, I don't like the smell, I had edibles like twice in my life, and don't plan on repeating the experience.
I still think that there is little logical reason to forbid people from consuming, and that it is especially hypocritical to do so while alcohol and tobacco are legal, and freely available.
And during the prohibition, black market flourished. The business will always be there. The question is do you support organized crime or do you support taxing to cover harm reduction and safety for people (buying from non-criminal sources, tested product etc)
Currently your stance is to provide money for organized crime
As has been stated already, past prohibitions didn't really work out that well.
I'd also add that 'mind-altering substances' is casting a really wide net, and could be argued to include stuff like caffeine.
I personally like Portugals approach of decriminalisation, because I think criminalising these substances usually hurts people addicted to them most, while helping those wanting to profit of addiction.