I know Man U were far richer than us but he still bought the best players to do the best job and I think Wenger seemed to want to do it on the cheap, even before we moved to the Emirates.
Ferguson would never have sat on so much money for so long, while we were desperate for top quality players in key positions.
I think you're right when you said about, "Fergie running his United squad into the ground."
In fact I think he did it on purpose.
He was only interested in winning the PL before he left, and wasn't the least bit bothered in leaving his successor a team that could still challenge.
It was the oldest group of players he had ever had, and he suggested Moyes, who he knew was out of his depth, as well as having an inadequate squad.
As for Mbappe, i would be surprised if we get him.
Wenger might have left and there is no guarantee the next manager will be interested.
If Wenger does stay, he is far too stubborn to pay more than 50m for a player that has slipped through his fingers, when he could have had him for less than half that.