Overconfidence (noun)

Excessive or unwarranted belief in one's abilities or powers, often leading to a lack of preparation or poor decision making.

Origin:

The word "overconfidence" is a combination of the words "over" and "confidence" which means an excessive or unwarranted belief in one"s own abilities or powers.

Examples:

1. His overconfidence led to a lack of preparation and ultimately a poor performance on the exam.
2. Her overconfidence led her to take on more than she could handle and ultimately led to her failure.
3. The company's overconfidence in their product led them to neglect market research, resulting in poor sales.
4. The team's overconfidence led them to underestimate their opponents, resulting in a loss.
5. The individual's overconfidence led them to neglect proper safety precautions, resulting in an accident.