We saw what happened in the Prohibition. When alcohol was criminalized, gang violence spiked, production was accidentally mixed with ethyl -and- methyl, tax revenues went down, and we as a populace was generally unsafer after than before. There were even cases where the US govt poisoned rumrunners' stocks to kill drinkers - they were doing something illegal, so US officials deemed it OK to kill people. It was bad enough that Congress and the president did another constitutional change to remove the ban.

With cannabis, it is mostly harmless and makes you feel weird. But as noted by Nixon and other republicans, banning and punishing cannabis users was being equated with targeting hippies and blacks.

And of course, cannabis usage completely ignores many health positive effects like prevention of nausea, glaucoma, and many others. It's not a cure-all, but the downsides are very very limited. Just compare this to say, the Sacklers' pushing of Oxycontin. I don't think "near harmless" can be used to discuss that.

When we look at harm minimization, making drugs illegal only pushes them underground, deprives tax dollars, increases violent groups to maintain illicit trade, and further reduces public safety. So yeah, you do have to look at the whole issue rather than "My uncle Jimbob sits around gettin' high". Whereas alcoholism and alcohol overdose is a significant issue which can kill people.. Yet we had that discussion a century ago, and we learned our lesson then.