I say this as a United fan, but Manchester United need to get over themselves. They're a "big club" in terms of past successes, the size of their fanbase and the ability to put those people into seats. That's it.
But this is not a good job to be offered. Any coach that takes this challenge on is a total gambler. Why anyone would think it's a desirable calling is beyond me. It's the worst job in the league.
You'll have no money to work with, directors and two sets of owners above you that have shown repeated ability to make poor or badly timed decisions. A squad to work with that's full of players who are either overpaid, lacking the required talent or are unfit. Youth system? Over the last several years that has tended to be overlooked by coach after coach that has had a need for talent, telling me that most of them don't see many solutions there. Then a degrading stadium, that again, there is no money to either repair, renovate or rebuild.
A catastrophically large amount of debt that can't be paid down unless immediate success arrived and a larger TV deal dropped out of the sky.
Then to top it off - no patience from the club, or a large section of the supporters, to turn the ship around slowly, as expectations are still incredibly lofty.
Man United are no closer to winning a league title than Brighton are.