If you read Phaedo and Aristotle, you'll see that Socrates, Plato, and Aristotle all believed the Earth to be a perfect sphere that was at rest in the midst of the Heavens. Aristotle goes into more analytical detail and also explains the primordial formation of the Earth from the elements as spherical.

Part of the answer is that space itself is spherical (that is 3-D), and motions in space are of three principal kinds: from the center, to the center, or around the center. They regarded the circular motion as superior since it most resembles the eternal or infinite, since circular motion represents also the concept of not having a beginning or ending. The motions of the heavens were considered circular and superior and also as occurring in 3-D space where there are the intersections of at least two distinct planes along the celestial equator.

They also considered nature as being complete and having an overall tendency to completion. For the Earth to be complete, which is also the best, in 3-D spherical space and account for the universal 24 hour day so well, all around the Earth, it naturally and logically should be a sphere.

The ancients didn't believe in Newtonian "gravity" to explain the position or nature of the Earth or to explain the motions of the planets and stars. They were right about that also. Newtonian "gravitational" theory is garbage. The Moon does not go around the Earth because of "gravity". It goes around for its own reasons.

Fact of the matter is, the more educated people are (academically or not), the less likely it is that they'll be flat earthers.

In the present, toxic atmosphere of "education" is this supposed to be a feather in the cap of GE or FE?

Might just as well say, "The more brainwashed people are, the less likely they are to hold a position which contradicts the brainwashing..."

Such a conclusion proves what,exactly?  That your esteem for modern, so-called education is far too great?