I am more talking about the long term. Total value of all currency is going to be +/- some % * k of GDP so over say 100 years you get minimal average inflation or deflation and the average keeps dropping as you increase to say 200 years etc.

But, even if it's value is stable in the long term that's arguably less important than month to month and year to year stability because you need to make loan payments today or buy food today etc.