I always look at alcohol prohibiton and what happened there.
The feds didn't legalize booze because they respected our rights. They did it to take over the booze industry. It's all about money.
They did it because Al Capone and his ilk were killing so many that it became a war at home--the government wasn't so much interested in taking over the liquor industry as they were in shutting down the illegal one.
Was making gangsters rich--the shit was ineradicable and unstoppable.
They did the right thing and gave up because the increased danger to others was not justified by the benefit of keeping the few from becoming debaucherous alcoholics (especially when they attended speakeasies ANYWAY and no one was being "helped").
This is the same way it is now. We want to save a guy from ODing in his car on heroin. He does anyway, but now someone like Pablo Escobar (who would've shot a baby in the face to save himself without batting an eye) is rich for it--instead of taxing it and regulating it and allowing all of us to benefit from its economy.
For decades we have been shipping the profits from one of our biggest imports across our borders. Whats worse is our country has dragged the world into this by refusing to do business with any country that isn't a signatory to the US-backed-and-conceived anti-drug treaties.
Prohibition was called The Noble Experiment, because it WAS born of a noble cause--much as this drug war has been. It failed--they found out creating a black market to stop addiction isn't worth it, especially when addiction levels appear to be rising in the face of such a market.
Many begged Nixon to end this craziness shortly after he signed the controlled substances act. A committee of his own creation unanimously recommended this, and he disbanded it and made no further mention (this is on record).
Eventually we'll figure it out. Illegal weed is not the problem, Illegal anything is.
This is and ALWAYS HAS BEEN a public health issue.