I, too, have a question, though I'll try to keep mine more neutral.
There is a common argument among some of the more passionate Round Earthers which goes along the lines of "I went on a commercial flight and clearly saw the curvature of the Earth from its cruising altitude". To my understanding, regardless of the Earth's shape, that claim is very tenuous. Assuming a round Earth, you shouldn't be able to see curvature from such low altitudes.
My question to Steven is: in your experience, is there an altitude at which the curvature becomes readily apparent to the naked eye? Could you provide a rough estimate?