acting against own self interest

One of the great mysteries of mankind was how people acted against their own self-interest.Points of pride ruined their lives.Envy and self-delusion took them down paths that led to nothingness.Why was it so important for people to maintain a self-image ? There were those who would never truckle, never flatter, never lie, never back down, never betray or never deceive.There were those who lived in envy and jealousy of the happier fate of others.

The Fourth K by Mario Puzo 

Jealousy quote

Jealousy is a strange transformer of characters.

The adventures of Sherlock Holmes by Arthur Conan Doyle 

Jealousy quote