I have made it clear that I will not support him any longer.

What can I do?

You can stick to your guns, although my bet is that you will still have him watching your dog and he will soon be back on your couch playing video games. You recognize that all of your well-intentioned efforts only enable him to continue along his chosen path. Somehow, he is getting the money for all of those bowls, where is that coming from? But I digress.

From his POV, all of his needs are being taken care of, either by you or by his girlfriend, he has told you in so many words that he's living the life he wants to live and Idk why you would think he'd change. You are trying to make him be something he actively does not want to be. You'd be better served to drop that project completely. Decide where your boundaries will be, enforce them and get on with your life. Also, if he is your only friend, you need to get more friends. If he's doing illegal things in your home, you could find yourself in some legal difficulties of your own. That will vary by location.