Let us go deeper into how a currency can come about.
No transaction between two persons is analytically pairwise
in an open economy. The root of the confusion lies in the
prevalent naïve-libertarian illusion that a transaction between
two consenting adults, when devoid of coercion, is effectively
just a transaction between two consenting adults and can
be isolated and discussed as such12. But one must consider
the ensemble of transactions and the interactions between
agents: people happen to engage in contractual agreements
with others; for them a specific transaction is just one piece.
To be able to regularly buy goods denominated in bitcoin
(whose prices fixed in bitcoin but floating in U.S.$ or some
other fiat currency), one must have an income that is fixed in
bitcoin. Such an income must come from somewhere, say, an
employer. For an employer to pay a salary fixed in bitcoin, she
or he must be getting revenues fixed in bitcoin. Furthermore,
for the vendor to offer a can of beer in fixed bitcoins, she or
he must be paying for the raw material, and have the overhead
fixed in bitcoin. The same applies to the mismatch of assets
and obligations on a balance sheet. All this requires a parity
in bitcoin-USD of low enough volatility to be tolerable and
for variations to remain inconsequential.