The thing is if you just had fighter-only gyms then most gyms would close down which surely can't be a good thing.

Incidentally, I never tell people I'm a 'thai boxer', I say I study thai boxing. I would only call myself a thai boxer once I'd had a ring fight. I wanted to do a full contact sport, I pondered straight boxing but the gyms I looked at were full of people 10 or more years younger than me and I would have been just a punchbag for them. Now in MT I know I'm improving in myself and from feedback from my instructors but I don't have a lot of confidence in my ability, I don't think I'm a natural and I think it will take a grading, i.e. a formal evaluation of my skill level, before I will have the confidence to fight. And the gyms are full of people like me, 90% of them will never fight. Most spar but not all, and they're happy with it.

So here is the question: Are you saying that ALL non-fighters should be turned away from the gym and not be allowed to study MT? If that's what you think fair enough, but where to draw the line? Should a gym only take people under say 25, because otherwise the fight career will be too short. Should they only take people who can reach a certain rank? Should they be kicked out once they're too old or if they lose too many fights?