Flat Earth is silly. Some people take the stance to be funny or play devil's advocate. Many seem to believe it along with other conspiracies.

From the beach or even several feet higher than the beach in Playa del Carmen, Mexico, you can see the high rises on the island of Cozumel. You don't see their bases or the land they are standing on. You just see parts of the buildings. It's super obvious the earth is curved here. It's one simple example of many that is accessible to anyone but conveniently ignored.

There are a shitton of simple or complex indicators that the world is roughly spherical. The "evidences" for the reverse are fringe or depend on deep conspiracies. You have to want to believe in the conspiracy or have very limited critical reasoning to think the earth is flat.