Buying power is not linear

Inflation is a complicated creature, it starts with creation of new money units, first it goes to financials and houses, then maybe after decennium or two, it is distributed to all prices, and then, when people discover that and expect it to continue, they try to rid themselves of the currency by all means, and then the hyperinflation is guaranteed, even overshooting by far what you could mathematically expect from increase in the number of money units.