The time cube was the product of a single, elderly, schizophrenic man. People in that demographic post to Facebook these days, I think.
Flat earth, I think, is caused by crazy people finding it easier to find each other with the Internet and social media, and putting together communities on the Internet.
The "main" Flat Earth Society (tfes.org) isn't made up of people that believe that the earth is flat - they are trolls. I'm sure there are plenty of 'True Believers' out there, but they're just as fringe as any other conspiracy theory.
Flat earth, I think, is caused by crazy people finding it easier to find each other with the Internet and social media, and putting together communities on the Internet.