Megalomania (noun)

1. A mental disorder characterized by delusions of power, wealth, or omnipotence.
2. A pathological condition characterized by a delusional belief in one's own power or importance.

Origin:

From the greek words "mega" meaning "large" and "mania" meaning "madness".

Examples:

1. The dictator's megalomania led to the destruction of the country.
2. The CEO's megalomania resulted in the downfall of the company.
3. The megalomania caused the individual to believe they were above the law.
4. The megalomania led the individual to demand excessive admiration and attention.
5. The megalomania caused the individual to overestimate their abilities and underestimate others.