system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Why does the wizarding world act like it is the "real" world and that muggles are some sub-class of people kept in the dark?

We must outnumber them by billions. If anything, they're hiding in *our* shadows.  

The wizarding world just seems... entirely ignorant of the broader scope of Earth.
gpt
Just the normal ethnocentrism you see in most cultures. Their world is real to them because that's the one they live in.  They rarely visit ours, or interact with it in any meaningful way, and many wizards don't even bother to learn much about our world, because frankly, they don't need to.  

Given all that, it's pretty natural that their behavior would exhibit a preference for their own world over ours.