Are you sure about that? As research in "Thinking Fast and Slow" by Kahneman shows, people exhibit the usual cognitive biases even while adamantly asserting they do not.
Did you check the cited research paper in that book, just to see that the experiments actually test for this, and the results actually match that claim?
It's bad but I found with Kahneman (and Taleb)'s books it really pays to check. The stories told in the books can sometimes be wild extrapolations of the actual research experiments.
For instance, did they test subjects' assertions for all of "the usual cognitive biases"? I doubt it. Or just one particular bias but extrapolated it holds for all of them, but on what basis? and is that relevant in the context of which you cite it now?
I urge you to actually go check. The outcome may surprise you. Tasty clever anecdotes with mildly counterintuitive experimental outcomes sell books.
We all do that. For example, I'll hold onto a bad investment because selling it means admitting I screwed up. It's a tendency we all have to fight.