I came across a flat earther in person once and what amazed me was how adamant they were about how they were right. As if it was painful that people weren't agreeing with them. Like they couldn't even fathom the idea that maybe its round. It was 100% what they thought, all or nothing. The embodiment of a closed mind.
I think the real question though is: who the fuck cares?
Round Earth, flat Earth. I still get up each morning, go to work, pay my bills and live my life and will eventually die. From a psychological perspective though, its pretty fascinating how the human mind can get so deeply wrapped up in conspiracy theory.