I am not a "boxing fan", I also don't watch combat sports on a regular basis. I have NEVER watched an MMA fight for example. But have competed. It's one of those kind of sports to me. I can understand competing, I did. I often can't understand what there is to watch. A bit like cycling.
Boxing is unique still amongst combat sports, MMA, and Muay Thai (the 2 other major striking sports), don't have close to the same amount of head trauma. In these sports, hits to the head aren't very common. The body, legs, and arms gets a bigger beating, the ones that do land clean on the head in these sports often do result in a knock out.
It's fairly well established that the risk in boxing isn't the knock outs, but the lengthy time of repeated blows. Which by the nature of the rules and the sport which makes it dangerous.
I wouldn't do it, but as a participant in other combat sports, I understand why people would. I don't see an issue with 2 consenting people competing in a martial arts contest. After all, which other martial arts do you ban? Karate, Tae-Kwon Do, Muay Thai, Aikido? There are lots of striking arts, and live training (against an active opponent) forms part of all of them.
This is something that doesn't affect the majority of people in their everyday lives, nor does it harm anybody else other than the participants. Children competing made me think though. Many also grow up thinking that they can kick a ball to fame and fortune, but most don't. Any career that draws fame and fortune suffers the same problems (apart from the likely brain damage).
But lets face it, the amount of brain injuries in boxing is absolutely tiny. I'd say that a child starting boxing, is safer than a child cycling on a road. Nearly all deaths have been in professional boxing, amateur level boxing in which most participants are, the risk isn't there.
If you're basing your idea of what really happens in combat sports, on what happens in a professional fight, you're mistaken. If you're so inclined, check out your local boxing club, and see what really does go on. It certainly isn't all about smashing somebodies head in.
Professional boxing has dangers that are unique to PROFESSIONAL boxing. Those dangers are not the same as in amateur boxing, but these aren't children involved in this. They're adults making their own free choice. You can't just enter a professional ring and fight, it's really not straight forward to get a license to box under professional rules.