People will and have believed whatever they wanted to. You may as well ask why was it that, in the 50s, people thought ducking under a desk would save them from an A-bomb, or even an H-Bomb. (There is a difference) The human race requires some kind of reassurance that everything will be ok. The illusion of safety, the illusion of progress, and even the illusion that none of this is real and it's just a dream is so powerful and comforting that people reach for it, even when it is so far away. Do you think that the New Deal really got us out of the Great Depression? Hell no. WWII did, but the New Deal gave the illusion of progress and thats why people want to believe that it's all a cover up, they want to hear lady liberty say "Every thing will be fine". Humanity needs, and will find, reassurance, weather it is there or not.