That's okay, until you try to use them as a substitute currency...which is why crypto-currencies are a good medium of exchange, until governments inevitably figure a way to worm their way into a controlling/corrupting position of influence.

Which brings us back to specie (gold and silver coin, or certificates redeemable in same), as the only valid valuable form of currency for the nation as a whole.

Any so-called "legal tender" law is void due to fraud, which proposes a corrupted "legal" substitute for real lawful money (about which see my other post here: https://steemit.com/anarchism/@hankscott/too-many-flaws).