I just figured this was one of those things that make you the ultimate hipster. Similar to drinking Old Style. You know it sucks, but you can't help but be different. That's how I look at this. They know it isn't true, but they can't help themselves but be the contrarian to everything, so this is the top of the mountain to them.
Although, it's gotten big enough of a push, that I think that it's become a, "How do I make money off of really dumb people without actually doing anything illegal? Oh, I'll throw this flat earth thing out there, if anyone responds, I know I've found my base of true idiots and I can milk them for a ton of money."
This is definitely in the realm of stupid or liar. You are either too stupid to realize how idiotic this theory is, or you are lying about believing in it.