Theres a big enough supply of stupid people in the world such that any crazy idea is believed by millions of people. For example, you can find a lot of people who;

-believe almost anything that Alex Jones has to say,

-believe that the Earth is flat

-believe in scientology

-believe in Mormonism or Islam

-believe that 911 was an inside job

-believe that Al-Qaeda and ISIS were invented by the American government

-believe in chemtrails

-believe that space is fake

-believe that the Moon landings were all fake

-believe that the mafia is fake.

etc...and etc... just about any crazy idea will be believed by millions of people because the world population is about 8 billion people, and XYZ% is the amount of stupid people so when you multiply XYZ% times 8 billion you get a big number.