"Money is the product of society, just as Bitcoin is the product of a society of computers. Money needs the greatest human network to succeed, just as the Bitcoin blockchain needs the greatest computer consensus. This network and consensus, however imperfect, is ultimately provided by the state in modern societies, just as it was the case in the many cases of recoinage and remonetization throughout history. For as long as we have states that strong and accepted by people, for better or worse, Bitcoin will remain a substitute currency."
What's wrong with it being a substitute currency? In the past states are the only people that have issued currency because it's in the power-hungry interests to do so, but whether bitcoin will succeed or even overtake a national currency is down to the people who use it. I certainly think it could become some sort of defacto world currency and one that I think we need just as a long as it's not controlled by a state.