Some of the ugliest disputes about inheritance are motivated by envy that has turned into hatred.
Often, they have nothing or little to do with the contents of the estate.
While there may be plenty for everyone, some people simply cannot endure the notion that someone else might have more than they.
Fights of this kind can continue for years—between nations, even for hundreds of years—and perhaps never come to a conclusion.
They are not really fights over material possessions; it is the pure spirit of envy that grows, that devours, that becomes a power unto itself.
Such a vendetta, waiting for the downfall of the other party, can become a person's sole raison d'etre, so much so that if such a person succeeds, life suddenly becomes meaningless.
–Rabbi Adin Steinsaltz
From "Envy" in Simple Words by Rabbi Adin Steinsaltz