HackerNews tech bros, chasing that upvote validation. When you've been rewarded all your life for being smart and right, you tend to think your guesses are right and announce them loudly.
HN users, much similar to many places on the internet, fall into the trap of believing that because they hold an opinion on a topic, they are therefore right.
Everything I know about the Dunning-Kruger effect, I learned on HN.
And no site featuring up/down votes, usernames, and publicly displayed logins will ever pursue the truth as a first cause, only to enable the ego.