I'm sure I would be surprised at the extreme delusion of players like Rashford, who have been repeatedly told for years how magnificent they are. And compared to the let's say 125,000 (123,694 according to AI) registered professional footballers on the planet right now Marcus Rashford definitely is still in the top quarter of those 125,000. But it's easy enough in his mind to justify his fall from grace over the last three years on everyone else but himself.
I happen to believe there still is an outstanding footballer in his boots, but he's got to get a grip on himself -- which is not a sure thing to happen. No top club will take him on as a project at his current wages. And if he comes back to Old Trafford, is he willing to work to reclaim his prior form and status? I have no idea.