To believe a flat Earth, it is necessary to accuse impossibly large amount of people from all over the world, spanning more than 20 centuries, to conspire together to deceive the rest of the human population.
On the other hand, to understand that the Earth is a sphere only requires simple observations that anyone can do themselves. In accepting that the Earth is a sphere, there is no need to throw a single baseless accusation to another person.
Much evidence for spherical Earth comes from a third party. In such cases, flat-Earthers can easily use their ill-feelings and extreme prejudice to dismiss the evidence. When that happens, there is not much we can do. It will be easier if we simply direct the topic to simple observations that we can do ourselves to prove spherical Earth. As they are personal observations —not information from a third party— there will be no room for flat-Earthers to use their extreme prejudice.
Flat-Earthers hate personal observations. In most cases, they will attempt to derail the discussion back to information from a third party —like NASA— where they are free to use their extreme hate and prejudice they got from flat-Earth indoctrination.
Due to these necessities to slander others, the majority of the topic in flat Earth indoctrination consists of baseless accusations to various third parties, including scientists and space agencies. On the other hand, in any scientific discussion, there is absolutely no need to throw a single baseless accusation to another person.
Slander, hate, and extreme prejudice are integral parts of believing a flat Earth. Once a flat-Earther can get rid of these ill-feelings, they will no longer be a flat-Earther.