Deep in my heart I still believe that the flat earth society is a massive joke on conspiracies, and one day they will come out and say "ha!!! you thought we were serious? super-gotcha!!!".
Many people are not joking. Which I use as a check on any time I start thinking "Surely people won't believe..." There are people who believe the world is not round, which implies that there are not many limits on what some people won't believe.
i sincerely believe that many conspiracy theories start as jokes or pranks. there are so many kooks in the world and now we are all connected. write and true believers you will find.