NOTHING OR EVERYTHing?

Riddle: What do the poor have, the rich require. It is greater than any mortal strife. All men carry this to their grave. What am I?

Answer: Nothing

Source: https://www.riddles.com/11260

What do the poor have, the rich require. It is greater than any mortal strife. All men carry this to their grave. What am I? — NOTHING OR EVERYTHing? by Yuhriel v1.

Riddle: What do the poor have, the rich require. It is greater than any mortal strife. All men carry this to their grave. What am I? Answer: Nothing — by Yuhriel v2.