Flat Earth pseudoscience is a symptom of anti-intellectualism
In the 1990s and early 2000s, a lot of the online presence of Flat Earth societies on various websites and forums was probably based on satire. With the advent of YouTube and the growing conspiracy movements, more and more people have seriously claimed that the earth is flat. Before, many cranks were often socially isolated and rarely encountered thousands of other people who shared their viewpoints.
With the Internet, it has become possible to connect with people who share your own worldview and experience enormous reinforcement. It is also very easy to become ideologically isolated online with search engines silently adapting to your search behavior and showing you material that the search engine algorithm has predicted that you want to see. This is ultimately done to monetize the preferences of individuals, but has the disturbing side effect of reducing the amount of divergent information that a person will see. It is like a form of technological confirmation bias. On social media, you also get to decide who you follow and who to block, further strengthening ideological isolation. Technological and social filter bubbles skew their world.
Ultimately, the Flat Earth movement is a symptom of anti-intellectualism. It is an extreme distrust of modernity and science on the base of a conspiracy theory that does not even remotely make sense even by the low standards of conspiracy theories. For some reason, all the governments of 200+ countries of the world have decided to fool people into thinking that the Earth is really shaped like a sphere. On the Flat Earth model, Antarctica is at the ends of the flat disc, and protected by the military. Why all the governments of the world are conspiring together and why they are trying to hide the supposed fact that the Earth is flat is exceptionally difficult for Flat Earth activists to understand.
Debunking Flat Earth conspiracy theories is thus one aspect of combating anti-intellectualism.