People who actually believe it are in the minority and are simpletons or mentally ill.
Sadly I know a guy who really full-on believes this... and that Roswell was real, 9/11 was faked and a bunch of other conspiracies. Wouldn't be surprised if he believes in chemtrails and owns a tin foil hat either. But he's pretty good with words and is neither retarded nor obviously crazy. It's like he's just decided the world is a sham, we're all puppets dancing according to some agenda and that warps his perception of everything else. It's like he's just waiting for Morpheus to show up and offer him the red pill. Even if you manage to push back and disprove one little bit of his ramblings it's like okay maybe that was wrong but the other 99.9% is still on.
It reminds me of some of those otherwise seemingly functional people who've been in ordinary jobs but end up fixed on some crazy idea that a Nigerian prince is offering them money or that they have an online girlfriend they never met who totally loves them and totally lose it. Many of these don't fit the "simpletons or mentally ill" who could never hold down a job profile. I saw someone else here mention Ben Carson, brain surgeon but thinks ancient aliens built the pyramids. No matter how smart you are, you see what you want to see. You believe what you want to believe. Then you use your brains to wrap reality around your beliefs, not the other way around.
That's how you end up with scientists with a religion full of facts science has refuted. It turns out people don't have to have one coherent set of thoughts. We actually live quite well doing a day job and believing in the first woman was made from a rib bone at the same time. It's just that for some the last kind of "facts" take over and consume them, to the point where they can't accept reality as reality anymore. Mainstream media (MSM) is fiction, my alt-news is reality. Mainstream medicine is fiction, my homeopathy is reality. And Internet is the greatest boon to alternate realitys ever, here they all meet to agree on how right they are. Most are pretty harmless though.