well my experience of several US states a couple months ago doesn't seem to show any overt signs of societal collapse due to weed legalization.
It's very much run like any other business.. In fact, far more strictly than many other businesses. ID required (even if you are clearly old enough), random lab testing of weed to try and ensure no nasty chemicals in the product people are buying etc..
Far safer than "make as much money as we can on the down-low" street weed. Hell I remember maybe 10yrs ago or so some Vietnamese crews were spraying weed with fine particulate glass to make it look more "frosty".
The increase in drug problem(s) in the US is much more centered around Meth and Fentanyl than weed. The US has a serious problem with opiod's.