They won’t admit it because his voters identify with The victimhood Trump spouts.
Why are all his most passionate supporters generally middle-aged / old white people? Why is the religious right so much in his camp? The rich?
They identify as victims.
Middle aged / old whites are so used to getting their way, so used to being born on 2nd base that when shit goes sideways it has to be the ‘others’ fault. Whatever that is. Deep state, immigrants, minorities, China, etc.
The religious right has been on the victim trip for way longer. But their 1980’s-today dance with the Republican Party has really amped it up. No prayer in school, abortion, falling church attendance, etc has all been due to the colluding forces of the devil, the secular left, feminists, Jews, Muslims, and the communists.
The rich are victims because their money is always under attack. They must at all times defend it from increased taxes or increased costs due to government actions. Much of those actions are due to the larger amount of the less worthy folks who aren’t of the same ilk as them. They view government / the public sector for those who aren’t smart enough to make it in the private sector. They view anyone not rich as somehow less than because the only really objective score in life is how much $ you have. That’s your worth.
There’s a lot of overlap between groups, I know.
But if they all are to admit that he’s not up to the task, then they’d be admitting that the reason their life sucks (well not for the rich.... they’d have to admit they were wrong which may be worse for people with egos that large) is because they aren’t up to the task.