It’s never a good idea to have a strong opinion about something for which you are willfully uninformed:
https://www.wikileaf.com/thestash/black-market-cannabis-2020/
https://www.city-journal.org/marijuana-black-market
And of course there is brain damage caused by long term use, increase in DWI / DUI deaths of innocent people, increase tendency toward violence from the brain damage, and all of the other social problems that go along with it.
"It is becoming almost routine across much of the country, law enforcement intercepting Colorado marijuana products being exported to other states."
Ah, so by 'Black market marijuana has increased' you meant, at the expense of black-marketeers in other states. OK ... what of it? The legally grown and sold product still cuts into the illegal sellers, wherever situated.
And of course there is brain damage caused by long term use,
Ditto for alcohol - which we've rightly seen as insufficient reason to ban that drug.
increase in DWI / DUI deaths of innocent people,
Increase in drivers testing positive for use that may have been weeks ago; where's the evidence for increased deaths?
increase tendency toward violence from the brain damage
Sounds like urban legend to me.