hubris
Extreme pride or confidence that makes someone act foolishly.
Hubris is excessive pride or confidence that leads someone to make foolish, reckless decisions. When someone has hubris, they think they're so smart, skilled, or special that the normal rules don't apply to them, and this overconfidence usually gets them into serious trouble.
The ancient Greeks used this word to describe heroes in their stories who became so proud of their achievements that they stopped being careful or listening to wise advice. A king with hubris might ignore warnings from his advisors and lead his army into disaster. A warrior with hubris might challenge the gods themselves, believing he's unstoppable.
You can see hubris in everyday situations too. A student with hubris might skip studying for the final exam because they think they're naturally brilliant, then fail spectacularly. An athlete with hubris might showboat during a game, so confident they'll win that they stop playing carefully and end up losing.
The key element of hubris is that it blinds people to their own limitations. Everyone has weaknesses and makes mistakes, but someone with hubris can't see their own. They've become so impressed with themselves that they've lost perspective. Hubris is why people say pride comes before a fall: when you think you're invincible, you stop watching where you're stepping.