To think, every single space agency in the world is lying about the earth being a sphere!
Every astronomer
Every scientist
Every aeronaut
Every astronaut
Every pilot
The list goes on and on!
Why would they be lying? 100,000's of people!!
Why?
I'd say it's obvious most of those people you listed wouldn't ever have to lie. Why would they? Astronauts went to the moon, don't you think they could tell the earth was a sphere or not? That's enough to stop anyone from questioning it, no matter what their degrees are.
Of course, some people would have to be lying, particularly the upper echelons of space agencies. The pioneers of NASA are well known to be immersed in a masonic society which is secretive by nature. It was a common masonic belief that they were carrying forward and guarding the mysteries of the Enlightenment. Copernicus, Bacon, Newton, etc. are considered apostle saints in freemasonry, using the measurements of science to illuminate humanity, yadda yadda yadda...
I'd guess the specific motivation lies around advancing an idea like the Copernican principle at all costs, which is the belief that earth has no preferential quality or position in the universe, i.e. the earth is nothing special, just one more speck among a nearly infinite amount of planetary balls flying through space.
Erasing the physical specialty of earth serves to erase man's history with his Creator. It replaces the particularity of revealed religion (i.e. holy scripture) with a kind of pluralistic universalism where everything is relative to everything else. This removes hierarchy out of creation and flattens the universe, which reflects back into the world of politics during the "age of revolutions" against monarchy... This is what the Enlightenment was all about... Overthrowing throne and altar, and that meant overthrowing the royal order of the universe itself.
But why want to do that you might ask? Well, listen to how modern philosophers talk... they all agree that the *particularity* of religion is evil and divisive and non-inclusive and bigoted, leads to endless wars, and ultimately holds back humanity from their true potential. Science and Reason came to save the world from the dark age of religion and illuminated it to a universal religion found by following nature.... (Nature's god)
So if those people are lying they would be telling themselves that they are saving humanity from themselves by promoting a view of the universe where relativity reigns and particular religions are false, to help bring us together into a global scientific utopia, etc. Francis Bacon wrote a lot about this vision and he is considered one of the founders of the modern institution of science itself.
Anyways, that's my guess.
I also have eschatological views related to this but I won't go into that here.