[RonF]

I went to school in the '70's on the East coast. The majority of people I knew used weed. A few used too much, classified as blowing at least one semester of school. I damn near did, though, although I wised up. The only people I knew who actually flunked out, though, did it while abusing alcohol.

[megatherium]

This matches my own experience: marijuana is not very good for you but heavy alcohol use does serious damage. I was glad when an old friend recently told me he'd stopped smoking marijuana and was "in recovery"; I stopped smoking it not long after college (20 years ago). But a mutual friend died of stomach bleeding as a result of alcoholism, some years ago.

Concerning Prohibition, I recall reading that cirrhosis of the liver dropped by about half in that era, a good proxy for how much alcoholism is present in society.