De la Hoya has a very bad reputation in the business world of combat sports. He has been in and out of court multiple times, and just lost the biggest commodity in boxing, Canelo Alvarez who said the exact same thing White is saying, that Oscar is an alcoholic drug addict who doesn't know how to run the business. Why would a guy like Alvarez, with a $300 million+ contract with Golden Boy go to court and demand to be released from that contract?
As far as fighter pay, it's a lot more complicated than greed. If you pay a main event too much, undercard fighters, advertisers, venues, ppv streams, etc will get less and you have problems. That's what De la Hoya did with Canelo. His huge contract made the PPV distributor complain and want money comparable to what Canelo was getting, so Oscar didn't now how to run the business and lost his main attraction. Look at Mcmahon's WBF experiment. Threw tons of money at the bodybuilders to get the names, but then didn't have proper money to build the brand. Then Vince tried the opposite approach with the XFL and had no name players but a shitload of money in promotion and branding and failed again. It's a fine balancing act to run a sports/entertainment business and Dana White is a master at it.