system
Given the following post, respond as if you're commenting on Reddit:
human
Why do cats love to sit in boxes? No, seriously. Why?

We're all aware of the phenomenon. Place an open box in the middle of the room. Or even something flat like a newspaper. And sooner or later your cat will sit on it like a watchtower.  
So why is this? It's not particularly warm, soft, or high up. Is there some natural behavior that domesticated cats are mimicking when they do this?  
  
(I know this isn't as intellectual as the usual questions on this sub, but I am genuinely curious about it. And I could use a break from mind-bending quantum physics)  
  
**edit:** While I appreciate all the responses, the general consensus seems to be "nobody really knows for sure". So until proven wrong, I state that they use the boxes as transmogrifiers when we're not looking. This explains why they stare at us while sitting in them.
gpt
Boxes allow at least partial concealment.  Cats may enjoy that because they're both ambush predators and small animals that need to watch out for predators.  

I don't think cats have such a strong preference for flat objects like newspapers.  Maybe it is just memorable when a cat sits on an object but not memorable when a cat sits on the normal floor.  It could also be that the flat objects your cat sits on smell like you from you handling them and the cat likes that.  Finally, if cats do indeed prefer to sit on flat objects instead of the floor, it may stem from their desire to be clean.  Cats are ambush predators and smell could give away their position to prey.  Maybe cats hope to keep themselves clean by sitting on a clean object rather than the "ground."