I sincerely doubt that "disouragement of the non-productive uses of capital" is the main reason for inflation. Linear tax on having money would do much better. Besides, except for a pathological example where scarcity of money causes deflation, why would it matter if someone is hoarding money?
If they're saving for something that costs e.g. 10 years wage, "hoarding" money is the only way they'd ever save that much. But with constant inflation, it's basically impossible - the only way to "save" money for something that expensive is to take a loan... Which again seems to lead back into banks' pockets. Who actually hoard money.
The game seems rigged, and all "explanations" for inflation just sound like bad lies given by Wall Street brokers high on coke.
Except that it doesn't. Money is created by private banks through credit (loan, mortgage) creation:
* https://www.bankofengland.co.uk/quarterly-bulletin/2014/q1/m...
* https://www.bankofengland.co.uk/explainers/how-is-money-crea...
> […] so my bills under my mattress or buried in my backyard keep dropping in value.
Yes, this is a feature: the discouragement of the non-productive uses of capital and hoarding à la Scrooge McDuck.
> No, you can invest money.
Most people actually save and do not invest:
* https://www.pragcap.com/saving-is-not-the-key-to-financial-s...