Well if I had to take a guess I would imagine he was perhaps self medicating by drinking too much(I've been there)...and is instead using cannabis now to help the anxiety or whatever he was drinking for as well as to stay away from the drinking. Not sure its an addiction per say....especially if its not interfering with his ability to function or goals in life. Four times a day is really not that much, especially if its just like four 'bowls' four full fat joints every day might point to some over-use however.

And well unless you know exactly how much they are making, how much they are saving and how much they spend on cannabis...you can't know for sure they're buying cannabis rather than saving. Have you inquired if he is making sure to save or has plans to fund the move? And does he have a lot of other current expenses? Also though if he gets through college and the masters programs I imagine he'd be able to find some stable employment.

I myself find cannabis really does a lot for my anxiety and PTSD symptoms, like helps keep me more calm which makes me more functional than I am otherwise.