dosulo,
Fair enough.
Short answer. Rothbard was talking about something becoming “generally accepted” or “commonly accepted” as a medium of exchange or a money. If you look up Wikipedia on “money”, that is the very first thing the article says about money. It has to be, by definition, generally accepted. And this is not some weird Austrian thing, it is the standard definition of money in the economist community.
When asked to please nail down what they mean by generally accepted, all economists give the same answer. There is no precise dividing line. This however, does not make the phrase meaningless. For example, “rich” is imprecisely defined, but a homeless vagabond is obviously not rich. Same with generally accepted.
“Medium of exchange”. also, implies a great degree of acceptance. The only difference between money and medium of axchange is one of degree, how generally accepted is it. Generally accepted = medium of exchange. Very widely generally accepted = money.
The reason for this proviso is that a few friends or weirdos or what have you who agree among themselves to use something or other as a coupon in their transactions does not make that something into a medium of exchange, nor into money.
EDIT: For the same reason, they did not insist that a money be universally accepted within an economy, because then three or four nutjobs who refuse it would negate it from being money, which is obviously not the case.
Bottom line, momey means almost universally accepted with in an economy. You can get anyhthing you want with it.
Mises Regression Theorm deals with the question, how does something become money, meaning, by definition, how does it become widely accepted and able to buy almost anything from almost everyone within a given economy. And of course, the first step, he concludes, is that it was used by many people and valued by many people for its non-exchange value, like cigarettes in a prison.
With all that preliminary info, we now see why bitcoin has not contradicted the Regression Theorem. It is not in comon use by anyone. You can only buy a couple of items with it. Certainly you cannot buy everything even a tiny store, like a 7-11 or a gas station that sells food and a few other things on the side, would stock. Let’s not even talk about WalMart.
And the few people who use bitcoin do not use it for all, or even most, or even 5%, of their transactions. They buy an odd slice of pizza, if that. What really interests the bitcoin guys is buying low and selling the bitcoin itself to the next sucker.
So that saying it is a money now, or even a mere medium of exchange, is laughable.