Because we're depressed at being surrounded by stupidity.

Or at least I am; I won't speak for everyone else.

And it doesn't help that we are getting deeper in the idiocracy timeline everyday.

Right there with you.

There's different flavors of stupidity. There's the "oh damn, why didn't I think of that first" and there's the smug "I did my own research and your evidence doesn't match by beliefs".

Stupidity in the sense of doing nothing good for themselves or anyone else, yeah. People are mostly a collection of local context clues about overly emotional nonsense.