This is so wrong that I don't know where to start.
First of all, people tend to forget that government is not made of angels. It is made of humans, who are susceptible to the same flaws as the rest of us: greed, hunger for power, etc. Therefore we should try to limit the power government has over us to only basic necessities.
Second of all, historically, human societies functioned quite well with multiple competing currencies on the same area, some of them private, some state-governed. It might have been pain in the ass if some customers wanted to pay in French coins and others in Belgian ones, but that pain was eased by the fact that they were made of gold or silver, so to compare their worth it was enough to compare weight.
Lastly, control of currency allows goverment to increase it's spending beyond reasonable levels with debt. Which of course happens at the expense of citizens. This is the sole reason government enforces it's monopoly on currency.
Cryptocurrencies are unique oportunity to take control over the currency from governments and put it back in people's hands, exactly how God intended it to be :) We shouldn't give up that control to easily.
In the end money is just a commodity, same as bread, so we should let the market decide which currency to use, without any monopolies, state-owned or other.