I think the key to what ObserverNeutral is saying has a strong point - "People will try to sell their fake, expiring "crypto-dollars" for real money, instead of following the rules.

Even if they can't see the "crypto-dollar" for less "real dollars", they will just go through some medium of exchange. I.e. buy toilet paper for crypto dollars, and sell it at a discount.

Great point. I didn't consider it offhand.