Instead of assuming, as the linked post does, that "I am right and those loonies are wrong", consider answering the question in the link, when applied to oneself:
“What if you got irrefutable proof that the Earth was round? You’d lose all your friends. Could you walk away from this culture you helped create?”
“What if I got irrefutable proof that [my belief X] contradicts evidence? I'd lose all my friends believing X. Could I walk away from this culture I helped create?”
where X can be "left-wing political values" or "Bayesian rationality" or "freedom of choice" or... you name a belief you hold dear and invested a lot of effort to create a group around.
I wonder if asking people "How would you test that?" when they make factual claims*, would work better than judging**.
Judging might be used because it requires less investment - especially when you don't have evidence, other than (set of people/"everyone") (assert) they believe this.
*I don't know if it would work if you only did it when you think they're wrong.
**See Slider's comment.
What is creating the problem is "you are wrong and we can't be friends" or "it's okay to bully people who are wrong". There seems to be two mindsets that are at odds. One is "you are wrong and it's important" and another is "you are wrong and it's not important". When those people have negative experiences when they are wrong I think they are experiencing wrongs. Pro-knowledge attitudes use being wrong as an opportunity to learn and be excited about new expertise areas you didn't know existed. If showing ignorance gets you diminished, depressed you fill try to shield from facing truth rather than strive to go towards it.
Being wrong doesn't mean you lose your human rights. Using an excuse of "he was wrong" for attacking someone is insufficient basis.
At one point the question is what are solutions "abandon them?" how about "stop abandoning them?"
Now in human communities thre is a danger that social status and technical expertise will become an undifferentiatted mess. One of the bad effects is that people can sell false propositions with their high status. But buying status with technical accuracy might not be any better. If you are wrong does it mean your needs do not matter and should not be met? A more refined norms set would probably treat these in different ways. How about you can lose your credibility via wrongness but never your human value? Maybe you should be able to socialise without having to risk say things that can turn out wrong?
If people are willing to bend their sense of reality to get attention you might get curoius whether you are giving your attention dues. People usually don't bend their sense of reality for giggles.
Counterpoint: It's emotionally draining and deeply unrewarding to try to be friends with someone who's wrong on a topic that you or they can't avoid for some reason (it may not be Important in any global sense, but it's important enough to one or both of you that it comes up even after you agree to disagree and that you can't/won't try to resolve it).
I'm happy to be casually friendly with plenty of people, all of whom are wrong on some topics (or wrong in their model weights across topics). I'm wrong, I'm sure, in many of these as well, and there are too many to try to crux every one of them. But casual friendliness is different from actual friendship, and likely feels like abandonment to many.
Granted there is some default relationship styles were you try to be on the same page for major issues and there is selectivity what those issues are. But whether there is a need to bring up a topic once a disagreement is discovered seems that it could depend on variables. Some people could even find discussing disagreements to be empowering and having a stance where disagreement means relationship is drained until disagremeent is resolved could be seen as a character flaw.
Oh, definitely. There are plenty of topics I bring up with my friends specifically because we disagree and it's entertaining for all of us. The key is that it doesn't generalize, and I can't replicate it with people that don't "fit" my style well enough and are in danger of joining a cult (or cult-like subculture) to get the validation they need.
The link was about a flat earther being drawn to likeminded sites/groups because they felt alienated in other circles. I submit that this is common, and also that your advice ("be nicer to those people") is not likely to work, because there's a good number of them that I just don't like enough to give them sufficient friendship to meet their needs. I don't bully them, but I can't really support them as much as they want/need.