I think the more seasoned political operators in the campaign knew they were going to lose, while the wacky yes men and women that were in the inner circle of the campaign thought they were going to win and win bigger than they did in 2016.
I think this is the right answer. What's harder to gauge is the proportion of seasoned operators to "wacky yes men". What seems to have happened is that seasoned Republican operators either said "screw it, I'm out", or got kicked out. We saw this mainly at the highest level, but I'm sure it happened downstream too. So it's likely that by the 2020 election, Trump's staff was increasingly made up of yes-men. By now, that's almost entirely what it seems to be from everything we can see publicly, and frankly I don't see how any serious operative can still stick with Trump for 2024.