Interesting stuff, how do you know this is how it works?
I was always around boxing. Boxed amateur in various gyms across the UK, boxed full-time in the military for a little while, and I was turning professional before I decided against it. I used to know that referee in the gif, actually. A few of my friends boxed professional too.
It's really not a glamorous game at all. Unless you had the backing of the few big-name promoters, you were really up against it. Small-hall shows for a few hundred pounds a fight, difficult match-ups, expected to sell your own tickets, working full-time as well as training. It's shit. I would have been a manager's worst nightmare, too. There's no way I'd have done anything to promote myself as I found it all wince-inducing. Literally the only part of boxing I loved was training and competing. I hated the fans and everything else.
There's guys on here (Che and Walter and maybe some more) who boxed at a higher level than me, I think. I'd suspect they likely had the same experiences of it over in the US.