First of all, this shouldn't be legal due to the fact that they are just kids, there's an age rule to all of these. This is something that's done illegally therefore no gambling site is going put This on the list of their games or even sponsor it. MMA isn't a weird sport but this category is actually awkward. These are kids that should be focused on their education and not beating their self up for other people's entertainment. I think if the government knows about this it's going to be shut down completely because it's considered to be illegal.
I was about to say that there are kids in shaolin temples that goes through hardship every day to get stronger, if people like you guys visits you will probably call it abuse, but that's training, not putting them against each other, so you guys are right about this one.
I plan to allow my kid to take karate classes, only if he wants, but that's just for protection, looking at the picture that OP dropped, those kids are going after each others throat, no form of protection is seen in sight, this is child abuse and I am surprised that the law allow such thing to take place.
It seems this world is fading away every year, the bad things are now looking normal is everyone's eye, what is going on? I will never place a bet on such sick idea called sport, this is far from been called a sport.