It affected behavior in ways that in hindsight were very counter-productive to economic stability: Every adult person and every business simultaneously tried to spend less, earn more, and hoard more -- which is impossible in the aggregate, because every expense by one person or business is income for another person or business. No matter what anyone did, the currency would lose value week after week, month after month. And everyone felt... powerless, unable to do anything about it.
John Maynard Keynes wrote what I think is the most insightful description of what living with high inflation is like: "There is no subtler, no surer means of overturning the existing basis of society than to debauch the currency. The process engages all the hidden forces of economic law on the side of destruction, and does it in a manner which not one man in a million is able to diagnose."[a]
[a] The Economic Consequences of the Peace (1919), by John Maynard Keynes.