Who founded the conspiracy in 400 B.C.E.?

The sphericity of Earth was known to the Greeks long before 300 B.C.E., and it appeared in the writings of Aristotle (384-322 B.C.E.), who was summarizing old knowledge. Indeed, Eratosthenes's excellent and famous measurement of Earth's circumference dates from 250 B.C.E. or so, long before Ptolemy's time.

That means this was all a conspiracy. How the hell did that happen way back then?

Hell, you can even look at the clouds and stars and tell the sky is curved!

*in sing-song tone* Don't expect an answer. *normal tone* Or at least not one that has any value or merits a response in any way shape or form (the shape being flat, which is obviously wrong).