Feel free to correct me, but the whole flat earth idea is mostly an Internet-era thing that is spread as a meme and nobody, apart from a _very small_ group of lunatics actually believes it.

In history there have always been true flat earthers, but they've become rarer and rarer until the Youtube era in fact, when the concept of it became so widespread because it's "funny" and not at all representative of how many people truly believe in it. The whole thing is people laughing at someone that doesn't really exist.