When I was a teen nearly everyone at least tried pot, it was so common in my high school people would smoke it in the restrooms between class and teachers would come in and just ignore those that were smoking pot. There were some that didn’t try it or use it again after trying it, some that became occasional users and a few that became dedicated to smoking pot and did it every chance they got.
It has been interesting to see those people in the years since- I have noticed no effect on those that were occasional users, but the dedicated pot smokers obviously had brain damage that was noticable after only a couple of years. Until I saw the change in the people I knew so well I thought pot was harmless. It is not harmless and I believe it is far worse than alcohol. There may be something to the idea that those that are prone to be dedicated pot smokers having different brains or chemistry/whatever to begin with, but I saw people that didn’t seem to have issues until they smoked it a while so have to believe their mental issues now are a result of using pot so much.
I had some friends who I knew before pot and after pot and I watched bright, ambitious, good looking girls attending college turn into wastes who dropped out of college and whose only interests were when they were going to get high, drunk, or laid.