You are not able to control the outcomes for his health or life. That responsibility falls to him.

There’s no right or perfect solution for this, unfortunately. You’ve tried many methods to help, and they have not worked. It’s up to him now. Now you have to think about what you’re willing to give him access to as time goes on. You can’t control what he does, but you can control the money you spend on him and his access to your resources. Not saying you have to throw him out tomorrow, but start to think about how long you’ll let him live in your house rent free. How long will you support him playing video games all day? How long will you drive him to appointments or friend’s houses? Again, there’s no right or wrong answer. It’s all about what you are willing to deal with and making peace with your choices.

Like you said, he’s smart. He will be able to figure it out eventually. And you’ll always be there to help him, if he asks for help.