I agree they're definitely the exception to the rule, most of that 'last mile' of going from ounces to a gram or two seems to be made up of people doing it on the side for a bit of extra money.
It does sound like the supply chain there is quite a bit different.
I disagree somewhat, dealing marijuana is still quite profitable, even in west coast USA where ubiquitous medical/legal marijuana has driven down prices a lot. As for east coast? From what I hear, the markup is still huge, with retail prices roughly double of west coast.
The only people I know of making a living exclusively selling marijuana (on the west coast) are small-time growers, though.
You're definitely right about crack/molly, the profit margins on those are ridiculous - because what's truly valuable there are the connections.
I'd wager that's who is behind this incident.