But Frenat you are forgetting that flat-earthers seem to absolutely discount any evidence from any source other than their own eyes.
By thinking there is a flat earth, they must also believe that the millions of pilots, engineers, sailors, air traffic controllers, governments, inpedendent space agencies, antarctic scientists, biologists etc etc are all in on one giant conspiracy to keep a secret from them that doesn't really help any of them in any way, fiscally or socially. For them, it wouldn't be hard to believe that a few thousand antarctic tourists/explorers are also fakes/in on the conspiracy.