i have trouble understanding how a forum of supposedly serious coders can be so detached from reality, but I do know that this is one of HN’s pathologies

I think it's more of a thread-bound dynamic rather than HN as a whole. If the thread starts positive you get "AGI tomorrow", if the thread starts negative you get "stochastic parrot".

But I see what you mean, there have been at least a few insane comment sections for sure.