I'm a heliocentrist who believes in a spherical earth by default, because I've never had any reason to think otherwise. When I say "heliocentrist", I mean the sun is the center of our solar system, not necessarily the center of anything else. Nonetheless, I follow truth wherever it goes, and in the search for that truth, I ask the following questions:
Have all of the astronomers who posited a spherical earth been wrong, and how have they all persisted in this error?
How is the apparent curvature of the earth explained, where it is seen from various vantage points, such as in airplane flight, or even from a tall building? I have even seen the curvature of the earth (or at least that's what I thought it was) from the top floors of a beach hotel, as I looked out onto the ocean.
Are all airplane pilots who travel vast distances over a flat earth, as well as those who travel in spacecraft, taken into a grand conspiracy, and pledged to secrecy as regards the lie? And have any of them ever "cracked" and told the public that it's all a big lie? That's a lot of pilots and a lot of astronauts (and, now, civilians who have no long-term connection to a space program otherwise comprised of near-perfect specimens of humanity who have "the right stuff"). Are they taken into an inner sanctum at some point and told "you will go along with the lie, or you will die, and your loved ones will die"? It would only take one, or two, or three, to "tell the truth", assuming they could "get the word out".
These are honest questions with no agenda behind them.