It is a byproduct of how money works you can check a sample here:

https://www.investopedia.com/terms/m/multipliereffect.asp

Basically, up to 0.9 dollar is lent to customer 1 with 0.10 in reserve who deposits in bank 2 .. who lends up to 0.81 to customer 2.. who deposits in bank….

So you end up with the “same” dollar being reused across the whole monetary system multiple times…