Mostly it comes from people who have no brain power and a little bit of a podium.
They don't care what they say, as long as someone listens.

"2+2=17"
"Uh, that's not correct."
"Shhhh! I'm talking!"

I usually preface statements involving medical terms with the idea that the closest I ever came to any kind of medical school was watching House.
At least I know I don't know anything.