Oh my god, I actually know one of these people. I tried to explain to him that by using a telescope you could see that other planets in the sky were round and curved and it wouldnt make sense for earth to be the only flat planet in the solar system.... and thats when he brought up that it could be possible the sky is a hologram created by NASA scientists. I had to walk away after 15 minutes. Also worth noting that he also believes that all world leaders are reptialians (alien space lizards) who can shapeshift and that Obama is the antichrist whos going to implement martial law in his final days as president...