The great thing about United is that it doesn’t matter who their manager is.
Amorim, Rangnick, ten Hag, Mourinho, van Gaal…they were all managers doing very well at the top level of the sport before going to United and none of them could turn the ship around.
Same with players, it doesn’t really matter how many great players they sign because they all get dragged down.
I genuinely think the only way to fix it is for them to give up on the idea they’re a temporarily down mega-club and just accept being Spursy for a bit. That’s what Arsenal did, and then as the pressure to win the title goes, things get less toxic and pressured, and you can actually rebuild gradually into being a contender without the players and managers being crucified for every loss.
Ratcliffe won’t accept that though, so they’re stuck in this cycle of new players/manager/owner bringing a slight pick up, then reaching new depths. And the slight pick up seems to get smaller each time.