There's some conspiracies out there that yes, do bear some serious consideration. The flat Earth thing though? Like you said... yeah... that horse be dead... but some people still no matter what continue to beat it. With facepalms, of course. In fact, there's nothing left of the horse anymore. But still. They will not relent.
That seems to be the problem, people without very good critical thinking skills seem to just believe every conspiracy. I think people are figuring out that government lies to them, and then they jump to the ridiculous conclusion that EVERYTHING they have been told is a lie.