I mean...
Smart bodybuilders, powerlifters, strongman competitors, and Olympic lifters are able to monetize their accomplishments in their sport through YouTube, training others, publishing a how-to-lift-weights book, stuff like that. I've seen some martial arts studios in my area and my city's premier MMA gym is a booming business. Expensive as hell too. I know, I paid for it. That's why I train with them.
However, two of my Judo coaches have other jobs. One of them is a cop, the other owns a construction company. I don't know what the third one does, whether or not she coaches Judo full-time.
There's a guy on YouTube who claimed there's a lot of money to be made in teaching martial arts, but because of my two Judo instructors, I'm just not sure... My former Judo instructors back when I trained in a traditional dojo definitely had different full-time jobs.
What's the deal here? I wanna run a Dragon Ball Z McDojo that teaches people how to Rasengan their attackers to the depths of Oblivion. But now I'm having second thoughts. (Not serious on this last paragraph.)