The hilarious thing about the flat earth Society is that people knew the Earth was round a lot earlier (like, centuries to possibly millennia) that most people think they did. Basically any culture that interested in Astronomy knew the Earth was round, including the Ancient Greeks, The Persians/Ottomans, and the Europeans during the Dark Ages, despite what most people think, as most of the knowledge from Greece that wasn't forgotten by Europe came from Aristotle, who knew the Earth was round.
People thought the Earth was round many centuries before people think they did, which is what makes the Flat Earth Society so ridiculous.