I’m a Gen-Xer, middle to the end of the generation. While I was in grad school getting my PhD in English (relevant to the story), I saw variations in drug and alcohol use. Without fail, the MFA (master in fine arts) folks did a lot more drugs than the MA/PhD folks. It was definitely a part of the “literature” culture — it was what writers did. It was part of the ethos. It struck me as performative as much as for fun.
On the other side (MA/PhD), I saw a lot of consumption, but it wasn’t for the experience as ethos, or leading to creativity, as much as to get away. The stress of a PhD is huge, and a lot of folks drank and partied (though not the harder drugs — mostly alcohol, occasional cigarettes while drinking) to blow off steam.
The other interesting thing I found. The people I knew that had done the most drugs — that had experimented all over the place — were the smartest people I know. They also had stopped a lot of the harder stuff by grad school.
Finally, a lot of my friends from that time gave up drugs (at least for a while) when they had kids. Not when they got married — lots of friends still smoked weed and drank, and all sorts of stuff with their spouse. When they had kids. The moms for obvious reason during pregnancy, but the dads, too. It was a sort of “well, time to be a grown up.” As the kids get older, I wouldn’t be surprised if folks go back to doing drugs. Especially weed in places where it is legal.
The millennials will find whatever they’ll find to combat whatever problems and fears they face — including substance abuse for some of them, experimentation for others, etc.