there are certainly legal standards for boxing that need to be abided for a boxing event to be legal. This includes having medical staff on site, a referee which manages the match, gloves being mandated for the boxers etc. If these standards aren’t held, you can charge a boxer for participating in an illegal fight and manslaughter should the other boxer die.

Fair point. Given how quickly these trends can pop out of nowhere, countries probably need to start creating laws covering general physical stupidity.