When confronted with direct evidence that they are profoundly wrong, they typically give a handwaving explanation such as, “It’s an optical illusion.” They can’t really explain what they mean by that, or they try and hopelessly fail, but that is apparently good enough for them. Desperately, they retreat to the apparent anomalies to which they cling. And of course they have to resort to, “It’s a conspiracy,” to dismiss all the actual direct photographic evidence. That is their all purpose get-out-of-jail-free card. They do all this while professing their activity to be, “truth-seeking.”
There is an intimate relationship between belief in a flat earth and conspiracy thinking. It seems that some flat-earthers start out as dedicated conspiracy theorists first, and for them the flat earth is the ultimate conspiracy. For others they go down a scientifically illiterate rabbit hole confusing them about the shape of the Earth, and for them this proves that there must be a giant conspiracy. Many other conspiracies then come along for the ride – because if the elites of the world can lie this big, they can lie about anything. It also means that they have some motivation to tell such lies – it must be part of their master plan to control the world. It is a “through the looking glass” moment, and they feel like they are waking up from the Matrix.