This is the problem, all pension systems are pyramid schemes. Plus you add extra overhead to administer over direct benefit contributions. You can claw some bac

This is the problem, all pension systems are pyramid schemes. Plus you add extra overhead to administer over direct benefit contributions. You can claw some back by keeping the shares of those who die early but it isn't enough. Additionally, dying early should still benefit your family and would do so under direct benefit schemes. You mask ask "what happens when people run out?" and the answer is the largely the same, it becomes a social program that is needs based just like it does for all the people today who have no pension.