Perhaps you could rephrase your question, as I don't think I comprehend it (and don't want to be accused of having ignored or misdirected the issue in my answer).
Galileo said that the world is round.
Newton said that the world is round.
Einstein said that the world is round.
Stephen Hawkings says that the world is round.
Today's top scientists say that the world is round.
The conspirators apparently secretly say that the world is flat.
Tell me; how do the conspirators know that the world is supposedly flat? Did god come down and tell them? Did aliens come to them and tell them?