Is he mentally unstable or unhealthy besides that one symptom? History of mental illness? TBI? What would happen if you took him on an airplane trip around the world from say NYC to London to Tokyo to LA back to NYC? I've never encountered such insanity except for online (in more ways than one heh) so this is pretty interesting to me.
Because they believe the North Pole is the center of the flat earth, I don't think this would convince him.
Taking a flight a long the southern hemisphere, though... flat earthers literally believe there are no flights between South America, southern Africa, Australia, new Zealand etc., because they're too far apart
This is like saying that the only time that I hear people say that the election was stolen is online, which is true. Yet there are a ton of people who believe it. I just don't associate with republicans / stupids.
You must live in a blue state. Or at least a bubble. Those people are everywhere so you should feel grateful that you think they are as mythical as flat earthers. (Maybe I should too I guess idk.)