This is a great explanation. I've long thought about these two conflicting effects, and I think as you pointed out it has something to do with what nowadays gets described as 'culture'. Dunning-Kruger seems to dominate in the 'everyone gets a trophy' culture in which I was raised; whereas in cultures that (at least in the way they speak about themselves) pride themselves on meritocracy, leaderboards, stack ranking, and the like, the impostor syndrome probably takes over.