Don't get me started on the fall of Rome, I could literally go on all day. Suffice it to say that was a symptom, not the cause, and their fiat currency kept prices stable even as the gold content fell. By the time Rome started losing territory, the population size across the empire had already fallen massively and the legions had been cannibalized in a list of ways long before then.

And regardless, that's not the proof you're looking for as deliberate inflation acts like a hidden tax on savings and we're not looking to increase spending, but rather change the manner in which we raise revenue. I.E. We can reduce inflation and raise income taxes for higher brackets, as long as net revenue is the same... Who cares?