People don’t like to admit when they are wrong. I get it. But the defensiveness of the average ball-earth bitter clinger needs to be pointed out for being exceptionally triggerable. But what accounts for their hysterical and predictable over reactions? What it comes down to, in my opinion, is fear:
There is the fear of being shamed for not having the correct answer. This ties into the fear of being out-grouped, stigmatized, and worst of all: the fear of being laughed at. Studies show that the average person fears public speaking more than death; that is, they fear public ridicule more than death.
Now take the Flat Earth topic. Let’s not call it a theory. For now, it’s a question more than an assertion. The topic asks “Is the earth really a ball?” more than it says “earth is flat.”
Extraordinary evidence is not required to state the earth is flat from one’s perspective, as this is not an extraordinary claim. Just look outside. However, the ball earth assertion is extraordinary as the claim relies on other claims also being true, most of which requiring specialized technology far out of the reach of the ordinary person. This leaves us with no choice but to put a great deal of faith in our scientists.
This explains why astronauts never have scandals or public falls from grace of any kind as most actors do. The astronaut is both a hero and a saintly person, sacrificing and dedicating their life for science, leaving the worldly behind.
So basically this explains it: the reason the globe-clingers are insecure: they can’t see the shape of the world for themselves and when the flat earther to tell them it’s looking flat, there’s no firm rebuttal other than “nuh uh” and “but muh CGI”.