Stuck inside our heads, we all know how much we're watching others, but fail to grasp just how much everyone else is watching us.
And it's called hostile attribution bias.
And it's called Campbell's Law.
And it's called the Diderot effect.
A phenomenon discovered by oil engineers after they spent too much on tracts of land in the Alaskan tundra also applies to all of those eBay bidding wars you've been participating in.
You might also recognize it in the subway, library, restroom, and other public spaces where people aren't typically very social.
There's a name for that: the Dunning-Kruger Effect.