I think region and product should be taken into account here. If you live in East New York or Bushwick in Brooklyn, two of the worst neighborhoods I can think of, off the top of my head, and you're a drug dealer, your top product is probably marijuana.... In the South Brooklyn community in which I was raised, I knew several people that made their living selling pot. Most of these dealers wouldn't go near any other drugs. The penalty was just too high and the profit too low.
As for living with ones mom, most of the dealers certainly did... Most eventually hook up with women who have regular jobs and the women then lease the apartment. They would get the women or their parents to lease them expensive cars or put their names on a cell-phone account. It's not as easy as it sounds to have a lot of cash.