Immortality gets very, very boring. You'd be surprised at how interesting the small mundanities of life can seem after a few millennia.
We may not say to the poor: "You have a right to fight the rich merely because they are rich and in order to make yourselves less poor. " We may say: "You have a right to fight to prevent the conditions of your life becoming inhuman," but we may not say, "You have a right to fight merely because you desire to have more and your opponent to have less. "