You are not enabling him. You helped him even though he doesn't see it. Chances are even if he became an artist there would be something wrong with that. I think it is fair that he pays an amount towards groceries. You are not using him. Sounds like the other way around for his victim type mentality.

Maybe there will come a time that you will be able to tell him that you are struggling too. Open up a two way conversation. Good luck with him and dont forget to care about yourself too.