Commenters have mentioned both Dunning-Kruger and Gell-Mann Amnesia. Gell-Mann Amnesia is rather strictly defined by its creator in the journalism domain, but

Commenters have mentioned both Dunning-Kruger and Gell-Mann Amnesia. Gell-Mann Amnesia is rather strictly defined by its creator in the journalism domain, but perhaps it could be stretched to include the commentary here at Hacker News. Still, I think that tagging your answer as "amnesia" does not work - unless you, yourself, manage to forget to be skeptical... on topics where you are not expert and commenters are still show-casing Dunning-Kruger. And it's hilarious how many of them there are here!