The problem, fundamentally, is that flat earthers don’t become flat earth advocates because they have a sane skepticism that what the vast majority of humanity agrees is obvious might be wrong, but because in the thin margin between coming across a “smart” flat earth argument and understanding why it’s flawed, they feel special that they “know” they’re above the vast majority of humanity.
Being able to design and run an experiment on whether the Earth is flat or not is legitimately cool, and might as well be seen as a source of self-worth, but because accepting the results means suffering the humiliation of accepting how stupidly over confident they’ve been in the first place, they can’t take the small L in order to score the big W.