The one thing that can get you fired fast: overconfidence

Let's face it, friends: You're either confident, underconfident, or overconfident - which the second two can cause some problems at work. I'll highlight some major points of the dangers of being overconfident, and why it can get you fired fast.
(Which we know that with underconfidence, we can improve. But, overconfidence may make you look like a butt)

Either way we look at it, overconfidence is a way to get ahead of the game. Not only do you think you're the best one in the workplace, but you'll think ahead of yourself all the time. You're always wanting the extra hours, wanting the chance to get rich quickly, but you never show your work true to your confidence.