It's somewhat Fati's own fault, as he didn't listen to the doctors to do a surgery and decided a traditional treatment. Like Umtiti. But he made a name for himself and that means he'll find enough teams to pay him a good salary, so he doesn't need to worry about money.
It was the opposite actually. At least when it comes to the knee (Umtiti case, and Fati initial injury)
Club asked him to go to Cugat, a reputable doctor that is too old now (over 70)and he kept trying to fix it with several arthroscopy that failed.
At the end he had to consult other doctors and menisectomy was the only way but it seems it was actually too late as the injury became bigger and could have saved earlier.
He was one of several players who had to consult other doctors and repeat surgeries after Cugat (Coutinho and Stegen too) before the club finally stopped pushing everyone to him.
He had already lost his game with those injuries, but then got the hamstring to add to it. That was the one he refused club advice. Which was understandable.
PS: that doesn't grant different results if he did surgery with someone else, although it looks like it.
Same way it is just fan fiction that Umtiti could have saved his career if he followed the club advice.