He probably has a great credit line, and loans from major banks, great relationships with senior guys at some bank in LA or Atlanta, that will throw him m's whenever, secured by his properties, or something like that. He probably has at least 15 million in properties. That are probably at least partially financed.
My aunt worked in banking and knows nothing about rap, but said rappers/celebs/ were notorious for going into debt on loans, and then repaying when they got a big check.
But, this is at BEST an exaggeration.