In Florida, 1.6M felons were "given" the right vote again (1). Most of the large elections in Florida are decided by less than 100K votes. The governor's race was more like 35K difference. Who do you think these ex-cons will vote for?
1) https://www.wsj.com/articles/florida-voted-to-give-1-4-milli...
By giving consumers, who are troubled balancing recreation and addiction, the proper treatment?
In my opinion, it's definitely easier to "handle" drugs when we can openly talk about them and their negative effects, without business and government telling us what to think about them.
What I found pretty eye-opening in the sense of "Oh wow, that's so obvious, I actually didn't think about that" was that one of the reasons was the American Prohibition in the 30s, and after it was abolished, a bunch of people were about to lose their jobs: https://www.youtube.com/watch?v=sXPOw2unxy0
Your mistake is to assume a simple relationship between legalisation and use, and that there are no benefits to those young people already using or who would use anyway.
Keeping kids out of the criminal justice system is a huge thing.