I think a lot of people believe the myth that the pyramids were built buy aliens, becasue they cannot fathom ancient civilizations being capable of such achievements without modern technology. I think the reason for this is that, for one, they do not understand that "Ancient technology" is basically just less refined, or analog modern technology, and secondly, while people understand that "many slaves" worked in the construction, I think people don't realize just how many of them there were. What is a rough estimate of the amount of slaves used in the construction of a single egyptian pyramid?