I think bitcoin is a world currency not a private currency and because he does not hold by the government and does not have tax.. and i am agreed for this currency. so all people are wrong tell us bitcoin is a private currency.
Bitcoin is not owned by one particular person or entity. Nobody has absolute control over its supply or issuance, the way that fiat currencies are run.
Thus, if you are talking about whether bitcoin is a privately issued currency, then no, I don't think that in legal terms it constitutes as that. Unless a crypto is actually centralized and its blockchain is controlled by some company or person, then they are all not "private".
If you are referring to the fact that bitcoin addresses are private and anonymous, then yes, they are. However, all transactions are public. I do think that you're most likely referring to private as in "private property", or in a legal sense, though.