The question concerning the motive why it is being hidden from the population that the world is flat in reality is also connected with the Impacts, that this truth that the earth is in reality flat would have on diverse aspects of life. Just take a look at the mentioned page and then you'll see very fast what the motive could be to hide this truth.
The crucial question related to the subject is: "What does it profit Satan / Lucifer when people are tricked, that the earth is a sphere?" Satan's gain from that the people think the earth is a sphere is, that the people doubt God, doubt the existance of God and the authority of the Bible (as the Bible also describes a flat earth).
FLAT EARTH CONSPIRACY EXPOSED! Rob Skiba Exposes the Flat Earth Conspiracy: Why They Keep it Secret