If "unknown unknowns"[1] make people idiots then everyone is an idiot and the term is neither an insult nor meaningful. Likely there's some other reason you have for wanting to use a mean and angry word that you haven't articulated well. What you describe in your original comment is probably just the Dunning–Kruger[2] effect.

[1] https://en.wikipedia.org/wiki/There_are_known_knowns [2] https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect