The majority of the members of the Flat Earth Society do not believe the Earth is flat. They are members because it's a counter-culture group which some people find interesting.

Those who think the Earth is flat are usually motivated by religious literalism.

The Flat Earth society consists of members who believe that the Earth is flat rather than an oblate spheroid. The group has been around since the 1960s. Some adherents are serious and some are not. Those who are serious are often motivated by pseudoscience or religious literalism.

Check out their website: Flat Earth Society

It's real; however, it's likely that most of its members are not actual believers in a flat earth.

The Flat Earth Society does exist and their official page is flatearthsociety.org. Most of those who do believe are motivated by religion.