>Why do otherwise smart people believe in something as stupid as simulation theory?
Good question. But do you really want the answer or just shitting to them because you don't agree with them?
Assuming that Truth is what you are seeking. Will give my two cents. First, people tend to explain happening with things/concepts with what they are familiar with. You can see in older religions this pattern a lot. Something along with A. Maslow "if all you have is a hammer, everything looks like a nail". Second thing, term "cargo cult". It is quite popular now in IT field, but not much people know origin of it. Term comes from WW2 era, when US army created military bases and airfields on some Pacific ocean airfields. Natives observed them, seen radio post (used for communication with planes), seen that planes brings boxes with goodies, and created their own "radio post" from sticks, leaves, wood and such materials. In result, it looked visually remarkably similar. Natives were operating from their understanding and perspective, they did not had concept of "radiowawes". Similar pattern you will notice in a lot of religions, when there was created ceremonies which imitated something, without much understanding/caring why it was done in first place. Similarly are for a lot of people in nowdays, they are thinking in concepts which are familiar with, and "simulation" concept, though quite new, is widespread and known enough to apply it. Also, it was used in cinema often enough, that people are "mainstreamed" and "bottle feeded" enough to apply that idea/though (movies like ExistenZ, Matrix, Inception comes to mind).
It is not that they would be stupid, it is more like that is a human nature.
