Well, I am in contradict. When we talk about bitcoin - much to say that it is "private" currency. Take a look, you may have the reason to think that it is a national currency because everyone could own it; however, if we would have tried to look, the only reason that makes the assumption false would be the basis on of who are the owners of bitcoin. Most probably, the one who can hold is the one who is also an investor of bitcoin. If we used logic, all people could be an investor, but not all people can win investment. Some people can be an investor; thus making him a private holder and as such used bitcoin for private - as in a private currency. Not all can be used bitcoin in a national currency such as it can be controlled by a government agency.