Well, I'm not a psychologist, so I suppose my interpretation might not be correct - the irony mounts.

But from the graphs you shared, it looks to me like the only people who underestimated themselves were the top performers. And from what I know firsthand with imposter syndrome, a competent person underestimates themselves.

I used hyperbole for effect, so I don't think that if you believe you have zero competence in something because you actually have zero competence means that you're secretly good at something. If you know nothing about plumbing, don't try to install a toilet.

But if you're working in the software factory then you don't actually have zero competence, you probably have formal education and some experience. Having that feeling that you might not be good enough is a sign that you're on the right track.