> Economies are improved and sustained by moving money, not by stagnant money.
A common misconception. The health of an economy lies in the goods that are exchanged; money is merely a placeholder. They are improved by producing more goods than are consumed, which creates room for investment in capital goods (tools for enhancing the productivity of goods and labor) and the research and development of improved technology (learning to make better tools).
"Stagnant" money just means that more goods were produced than were consumed, and the surplus was not actively invested. The surplus still exists, and continues to fuel investment (by others) so long as the money remains unspent. The "stagnant" money is off the market, not competing for goods and services, and as such contributes to a reduction in prices similar to what would occur if that money were simply destroyed (albeit temporarily), shrinking the money supply. In effect this leaves the decision about how the surplus of goods should be invested up to other market participants.
If the owner of the "stagnant" money knows of ways to invest which would provide an ROI better than the average rate of return on the market (i.e. the rate of deflation) then they should do so, earning themselves a profit and raising the average rate of return. However, below-average investments—malinvestments—would lower the average rate of return and reduce overall economic growth, and ought to be discouraged. It's better for everyone for the owner to simply sit back, "hoard" the money, and receive a passive reward for producing more than they consumed than it would be for them to actively invest in ventures with below-average realized returns and thus divert resources from better-performing ventures, but that is exactly what an actively inflationary monetary policy encourages by driving people who lack the competency to choose good investments to invest in the market anyway merely to avoid losses due to money supply inflation.