If you feel like an impostor, then you almost certainly are one. Most impostors probably don't even realize that they're impostors.
I've never felt like an impostor, every day I have the opposite feeling.
However, I don't agree that those people are imposters unless they're really being paid to contribute at a higher level than which they're capable of doing now or after an appropriate amount of "getting up to speed" at their job, which can legitimately take years, and meanwhile their peers are contributing enough.
Employers ask for a lot, but they often don't expect to receive it or don't know when they aren't receiving much, and in either case the employee is doing satisfactory work!
Do you believe that those people are all impostors?
No doubt Tom Hanks put in a lot of effort, but fifteen years into his career he was being paid tens of millions of dollars and getting nationally feted to go onto a movie set and do his thing. All of those people, simply because of the scale of the US and how the economic/legal structure operate, were at some point just way more rich or influential than it's natural for anyone to be, often too soon.
The people I've personally known most subject to impostor syndrome are programmers early in their career who slacked off a bit in college who are suddenly making close to or more than a hundred thousand dollars a year to do something they didn't have to work all that hard to be able to do. The sort of people who put in 70 hour weeks even in college never seem to feel it. (Neither do cooks)
The management fees and bonuses are just the cherry on top.