Offer your thoughts or opinion on the input financial query or topic using your financial background.

The life cycle of money
I'll answer but avoiding discussion of M1, M2 etc, too pedantic. I don't believe you are asking about the lifetime of either coins or paper money. I think you are referencing the fractional reserve system, and how a good portion of the total money supply is created by the banks lending out their deposits in effect 'creating' money. My answer to you is that if all loans were simply paid off, no mortgages, no car loans, etc, the total money in the system would collapse to some reasonable fraction of what it is today, 10% or a bit less. This comes from the fact that the reserve requirement for most large banks is 10%.  I'm referencing money, but not bills or coins. Think about what you make in a year. How much do you touch as paper money? For my wife and me, it's no more than a few percent. Most goes from a direct deposit to online payments. So this would be the subject of a different question altogether.  Let me know if this addresses your question.