Common with difficult children. They don't like rules and nobody is "the boss of me." It isn't a good trait. I do think father is enabling him from working, however you can't control his father anymore than you can control him. Where does he live? Does he have to pay rent, pay for his cell phone, pay for car insurance, fill up the gas tank? If not, our slow to launch children tend to stay Peter Pan-like. They are not motivated from within so, without any reason to work (such as lack of money, lack of housing, lack of toys, lack of car) they tend to sleep in, do little, and often use drugs.
I'm sorry that he quit his job, but not really surprised. That is part of a difficult child mindset: "I don't want to work or have to work. Daddy will pay my bills and I can just have fun." They still think of us as daddy and mommy, rather than adults who have their own lives too. They think of us as somebody who has to support them forever. It's sad, really...sad for them and for us.
This is your golden years. Amazing that you have such a young son. Honestly, it is certainly your own choice, but don't you want to enjoy your golden years without your son's drama?