What I find quite funny is that the Flat Earth Movement will never get far enough to ever become the dominating theory. It has nothing to do with the rest of the world being too ignorant of themselves or anything like that, it's just has way too many holes given its immediate assumption that the Earth is flat. There are just too many inaccuracies for it to be taken seriously.
Einstein's theory of special relativity was a new radical idea that took off because of the failure in the michelson-morley experiment. It started with a simple assumption that the speed of light is constant in every frame of reference. This in itself had many consequences that was completely new to the science community, but the difference between this theory and the FET is that it didn't have any holes. It made sense. It didn't contradict any other scientific laws.
The FET was born because initially it looked flat. With this starting point, all the consequences thereof that have grown into the modern FET still don't coincide well with what has been observed to be fact. At this point in human's history, the only reason FES is still alive is because of ignorance.