Who are they? Certainly not scientists. The notion that the earth was flat was the position of religionists.
And like the ignorant/illiterate 'earth is flat' people of centuries ago, YOU keep repeating nonsense that has been totally refuted.
The myth that Christians in the Middle Ages thought the world was flat was given a massive boost by Andrew Dickson White's weighty tome The Warfare of Science with Theology. This book has become something of a running joke among historians of science and it is dutifully mentioned as a prime example of misinformation in the preface of most modern works on science and religion. The flat Earth is discussed in chapter 2 and one can almost sense White's confusion that hardly any of the sources support his hypothesis that Christians widely believed in it. He finds himself grudgingly admitting that Clement, Origen, Ambrose, Augustine, Isodore, Albertus Magnus and Aquinas all accepted the Earth was a globe - in other words none of the great doctors of the church had considered the matter in doubt. Although an analysis of what White actually says suggests he was aware that the flat Earth was largely a myth, he certainly gives an impression of ignorant Christians suppressing rational knowledge of its real shape.