Don't get me wrong. I think everyone ought to know how to fight. If everyone knew how to fight the world would be a lot better place for several reasons. But prize fighting, well, it all depends on the draw. Depends on who knows what how. I've seen more than one "I've got a black belt" idiot get their ass handed to them by someone who learned to fight on the street where there are no rules and it was a matter of survival to learn that stuff.
So much of martial arts is done in a formal manner. It's done for toning, for conditioning, and yeah, some self-defense (but what you really learn about self-defense is not fighting). It's a recreational sport activity. And, such places are ligit, they are above board, they have insurance and all that. There is a lot of stuff they don't teach, and that they don't practice because its stuff that gets people killed or seriously hurt.
There are other dojos (perhaps not where you live, but for sure around here) that are no more than storefront training schools for thugs. Learning to really fight, like not moves, but a hail of ultra violence on a whole different level. They learn the stuff that hurts and kills, the weak points - like, you know a knee only bends in one direction, and if you kick it in any of the three other directions it's going to cripple the person. And, people are all into protecting their face and body, how many people practice protecting their knee? And the people who know and learn that stuff, are people who are used to using casual violence as the basic means of getting what they want. Granted they might use that prize money for hookers and blow - still, it's hookers and blow for them, and nothing for you. They like those odds.
Then there are guys like my brother. He never took a fighting lesson in his life. But he did spend 10 years straight in San Quentin the hard way (among other fine state institutions) and you don't ever, ever want to fight him. He'll just kill you. To him fighting is not a sport, or an activity, its what you do to prevent rape and to prevent people from killing you. He's currently out of work. Perhaps he needs that money.