Because we don't know what its like to be successful while hiring and sacking managers, so United fans are terrified to sack the one manager that has been the best since Fergie.
Also If we sack Ole people fear we will hire the wrong manager and the worst will happen because we've experienced the this more than once already. Our worst = No top 4 and building a shit squad.
What we need to do is put ourselves in a position where hiring the wrong manager and the worst happening is actually still a decent season. For example if Madrid hires the worst manager they could possibly get they will still make top 4 and pass the group stages of CL and the most important thing is their squad will still be strong for the next manager to come and turn things around.
I think that is the problem and why we fear a manager merry go round. United fans from experience dont have that assurance like Madrid does that even if they hire the worst manager they will still make top 4 and the squad will still be strong for the next manager to come in and turn things around quickly.
The counterargument is that we risk entering a state of perpetual timidness where inaction seems to be the only viable choice. Change always entails risk, these two go hand in hand. But most times, change is a necessity. And when you become afraid of change, even though deep down inside you know that you must move on, you'll always find reasons
not to take the dreaded step forward. Until the safety and the security you treasure turns into stagnation. Then you watch others pass you by and you're left wondering where the hell did it all go wrong.
I can guarantee you that if we settle for top-four finishes now, the most probable outcome is that we'll soon find ourselves outside the CL spots. We need to keep pushing for better things. It's also kind of tiring hearing people say that "if the next Pep/Klopp becomes available, i would trade Solskjaer for one of them" when, judging by the context of their posts, the truth is simple: No, they absolutely wouldn't. They would always prioritize the sense of security they feel now.
I mean, i can do it too. Let's say this happens back in 2015: "What guarantees are there that Klopp will be a good fit for us? He had a short 3-year cycle at Dortmund and by the end of it, all he left behind was ash and debris. He almost got the relegated and then he jumped ship!!! Is this long-term vision we want at United? Hipster manager, i'd rather stick with Solskjaer and allow him to see the rebuild through".
Or:" Pep who? The one managed to be successful in a certain environment and with the best player in the world accompanied by several other generational talents? What did he achieve at Bayern, outside his safety zone?".
I'm exaggerating, of course, but the point still stands. If you are so afraid of change, the next best-of-class manager will always remain elusive to you. You'll always find a reason not to take the risk. Then, he'll go to your rivals and you'll be left wondering "God, i wish we could find someone like him".
It is what it is, and we can't migrate the club to Italy or Spain. Our best guaranty is the quality of our team. In the end, what are we building it for? To win things, or to make up for the manager's shortcomings?