Boxing is not like the NFL or the NBA where you can buy a franchise and the franchise has a set number of guaranteed games every year, a gigantic regular guaranteed amount of money from TV every year, even very predictable guaranteed income from merchandising/food and drink at your stadium/arena etc.

Professional boxers don't have a pot to piss in when they start boxing for a living. There wouldn't be any fights at all if it wasn't for a bunch of sleazy fuckers putting up their own cash to put the fights on. And it's not a guaranteed thing -- plenty of people have tried and failed. You've got to subsidise a whole bunch of fighters, put them on a wage and pay their expenses and hope that some day one of them makes you some money and you can turn a profit on the whole enterprise. The regulatory system in boxing -- such as it is -- the sanctioning bodies, local commissions and so on has just evolved around the money guys who put the fights on. Various commissions operate basic health checks and supply officials and so on with their costs ultimately borne by the promoters (places like Vegas are a little different, the casinos basically fund the Nevada commission). The sanctioning bodies exist to make a profit too. They basically rent belts to various promoters so that their fighters can fight for and hold "world" titles.

The bottom line for boxing is that it's impossible to create what you have in other sports. There's no team or brand that can go on for ever, no leagues with guaranteed games/TV coverage/merchandising/sponsorship and so on for your team. It's just that bunch of sleazy guys putting their cash up in the hope of making a profit. And because it begins and ends with the promoters the whole structure of professional boxing can't be altered.