Since you are a professional who has happened to make it with some level of success, you know firsthand that there are a lot of excellent people who didn’t manage it for one reason or another. (And it’s not always because of lack of talent, they might have just gotten the wrong injury). How did they manage things when they finally came to terms with the fact they wouldn’t make a living doing that? What did they have to fall back on? Are they coaching? Teaching? Selling real estate or insurance?

There is nothing wrong with him chasing his dream, but make sure he has an alternative planned. Make him talk to some of those people, and find his own path. Hope for the best, plan for the worst.