You underestimate the power of big pharma, tobacco, and alcohol lobbyists here and the for profit prison industry.
That's not even throwing in the DEA, (some) police unions, and all that other stuff that don't wanna see it legalized.
But if you weigh up the profits from big pharma and the new commercial cannabis industry, the latter is probably now more profitable. There's not just the weed itself, but the jobs in all the related industries; glass-makers, shop workers, delivery services, hydroponic equipment production, administrative work. Just look at
@Snakegang
. He's part of the new economic miracle of marijuana legalization.
As for private prisons, they get kids on other shit these days. Just look at young people's music for example. It went from 'Love's Gonna Getcha' to 'In Love With The Coco'. And a lot of kids are dumb enough to listen to music like that and do what it says.