If you have so many skills, why don't you open your own casino?
I heard it is a very lucrative business!
Well it is absolutely different types of businesses when you selling a product (even digital) or service (your own casino).
Not all people would like to build service selling business as it requires a lot of marketing, working staff, there are a lot competitors and so on.
Also he don't need just skills for building his own casino but also huge budget for bankroll and marketing campaign.
I think if he like development then the best business for him is to sell scripts, games etc.