hubris (noun) - excessive pride or self-confidence; dangerous arrogance
[Our Wednesday Wildcards are fascinating and important words that are not derived from classic roots.]
ORIGIN: Hubris is a back-formation from hubristic or else from Greek hybris "wanton violence, insolence, outrage," originally "presumption toward the gods." (Online Etymology Dictionary)
“Hubris consists in doing and saying things that cause shame to the victim…simply for the pleasure of it. Retaliation is not hubris, but revenge. … Young men and the rich are hubristic because they think they are better than other people.” —Aristotle
I've always loved this word because I think it explains much of the world's history (the bad parts).
Even worse, social media has shown us that it doesn't take much more than one other person to agree with you to give birth to hubris.