But, the people who believe in the round earth never change their theories and, as of yet, I have seen little evidence (other than conjecture) to prove that this theory is wrong.
RE'ers change their theories all the time.
People come here claiming that toilets flush in the opposite direction in the Southern Hemisphere, and when we show them the Snopes page, they change their tune.
People come here claiming that gravity is proven and is caused by a curvature of space time, and when we point out the fact that scientists don't know whether gravity is a bending of space or a subatomic particle called the graviton, they change their tune.
People come here claiming that Christopher Columbus proved that the world was round, and when we point out that he did no such thing, they change their tune.
People come here claiming that the earth is round because raindrops are round, and when we point out that raindrops are actually flat, and that it's a bad analogy anyway because raindrops are held together by surface tension and the earth is not, they change their tune.