I’ve seen tons of public service ads recently claiming smoking tobacco will kill you and vaping will maim you, but not a single one claiming smoking pot will kill or maim you. Based on the accuracy of the former two claims, common sense indicates the latter is harmful.
For whatever reason, we do not discuss any problems or dangers of marijuana. Yes if smoking cigarettes is harmful, it makes sense that smoking and inhaling another substance would have similar harm. But we aren’t supposed to discuss that issue with marijuana.
It’s certainly a danger, but people smoke tobacco and other nicotine products differently, since they are highly addictive.
Not many potheads are smoking 20 joints a day.