Currency is a motivational tool for people to get rewards for their hard work. If someone doesn't get any reward for their work, why should they do it? Human brains work on a reward system, and money becomes a learned motivator so it therefore becomes motivation if money is a reward for a task.

If every human was polled "Is the taking of a life immoral?", almost all of them would say that it is immoral.

There is no self.