yup, this type of "expiring money" would just lead people to store wealth elsewhere. You could argue that this has already happened with long term low interest rates. I think a big part of the continued stock market and real estate bubbles is that interest rates are so low that there's a real disincentive to store cash in the bank, so folks put their wealth into houses and stocks.

Also, since when did "saving" become "hoarding"? Saving is a very important part personal financial wellness and business investment. Our goal should not be incentivizing people to spend money as quickly as they make it.