There is an interesting example here, though not a nice one, of how boxing works compared to other sports. Helenius is supposed to face Kownacki on the undercard of this bout. Their rematch has been postponed four times so far, mainly because of Covid. Helenius doesn't have a team behind him, thus he has to pay for his training himself. 4-6 week training camp, facilities, sparring partners (preferably good ones if he can find them), their salaries, foods, travelling etc. and one such camp costs tens of thousands to set up. Now he has had four such camps without any income. He was in debt beforehand already, and one of his bigger financial supporters quit because of Covid. The prize he is getting from this bout is a good one, but when you subtract these four camps, taxes, managerial fees, WBA fees etc. he won't pocket much, if anything. Being a member of a promotional team is vital for a fighter. And even though the greedy promoters cuts several types of costs from your salary, it still is probably better and cheaper than going solo
Wilder camp are deluded Deontay Wilder Trainer Believes Rumors About Tyson Fury's Sparring Woes Are True - Boxing News
So, let me get tis right... Fury was afraid to rematch Wilder the first time bevause Wilder hit so hard. Fury wife was scared. Ok. Fury rematches him, wins. Now.... Fury is getting beat up in sparring, and he scurred, again. Riiiiiighhhht. Mmmmmmkay.