Show me someone who deep-dives into flat-earth and I will show you someone with above average intelligence. It is precisely those with average or below average intelligence who accept what they are told without a sceptical eye.
Discussion
I - without much thought - reject the flat earth "theory".
Why?
It's _not_ because I "accept what I'm told without a sceptical eye".
It's because trying to fit my banal world experience (plus all third-party evidence I'm aware of, along the lines: "didn't get to an edge on the ocean while trying to cross it") with the flat earth topology indicates a low probability.