I've always thought about it this way: We trade our time (work) for money and later trade that money for time (other's work). We see this manifestation in lots of places: bus is cheap but also costs time vs limousine is expensive but uses minimum time. Growing food is dirt cheap but also costs time vs buying produce is expensive but uses minimum time. This exchange has also allowed the producers to invest in efficiencies and economies of scale. All told, this is why I generally have a rule to not spend money on anything that doesn't buy me time, it is my most limited resource.