Anyone who thinks he doesn't still smoke weed is dreaming.
If you had a kid around 14 start up...and goes to a pretty good extreme by eighteen years old, then continues on for at least four more years...I’d say that you can’t ever quit the stuff. When you get into a stressful situation...you will crave it greatly. I could see someone forcing themselves to limit it to once a week, but I doubt that you will ever go completely clean.
The other curious thing about this whole story....is that he smokes a heck of a lot at Occidental College...likely failing various courses and I suspect was asked to leave by the end of the second year. Then strangely enough, you get accepted in prestigious Columbia University in New York City. You’d have to repeat various classes, but the timeline never shows that. So I would imagine that a bogus Occidental transcript was created, and layered into mess. He probably gets some help with inside grade manipulation, and passes enough to graduate two years later.