With commodity money, real wages tend to increase, as does the standard of living. With fiat money, real wages tend either to stagnate or decrease, as does the standard of living. There is good data from Great Britain going back almost 200 years attesting to this. Interest rates are much higher than with commodity money. Commodity money facilitates real growth by investing savings, thereby causing increases in physical and intellectual capital.
Fiat money results in nominal growth and less real growth.
Eventually real growth and real earnings decrease. Capital is destroyed and there tends to be less replenishment of physical and intellectual capital. As productivity increases, prices tend to decrease, thereby resulting in more goods for more people at lower prices. This is what an increasing standard of living means. Prices tend to increase or, at best, remain stable.