> I think this comes from attaching their ego to their opinion, so if they're wrong, then they're "worse" of a person, so they really don't want to be wrong. Perhaps it's also a form of sunk cost fallacy.
Mmm. I've seen similar things but I interpret it differently. People literally can't think that quickly - it takes a few days (!) ideally involving a some good sleep to really synthesize new ideas.
That time required to think implies that even if someone is convincing it still makes sense to plow ahead with disagreeing with them in the here and now.
1) It is possible that their certainty is convincing but not their argument. In my early days on HN that happened to me a few times - I got convinced in conversation because someone seemed confident despite having clearly understood what I'd said. Later I swung back to my initial opinion later after reviewing the arguments carefully and deciding that the compelling part was flawed.
2) Even if the argument is compelling, it still makes some sense to just throw out all the arguments you have, shotgun style, to find out what the appropriate counters to them are in the future.
Regardless, I'm pretty sure people do change their minds, it just happens a bit slower than people expect so nobody notices it happening. Of course, there is a particular style needed to achieve that - if they get threatened or attacked while changing their mind they will not do it.