I think the “dumbies” and “smarties” part comes to play when people decide or not to open their big fat mouths and share their “great knowledge” in a domain they have barelly learned about, especially when they’re dismissing expert opinions with their “great knowledge”.

So whilst being in that very special point of the Dunning-Krugger Effect isn’t really a metric of smarts (we’re all there in at least a few domains), the likelihood of actually dismissing the opinion of domain experts when one’s knowledge in that expert domain is at that point of the curve, is probably positvelly correlate with dumbness.