Neither bitcoin nor paper money has any real value, but notes have national credit support, and what if bitcoin also gets national credit? The government will lose its macro-control policy but it can also effectively eliminate inflation, two relative ratios. Is that a good result? Of course, I know that the government is very unlikely to support bitcoin, but who knows?
But they never support crypto currency as their national currency.Because it can destroy the governments revenue so they will keep their fiat money as their national currency forever.But if they do then it will do more benefits to the citizens not to the governments.
I am not being pessimistic here but I do not see for now that the government will accept cryptocurrency as our main currency. Because of the reason you have mentioned. In this world where money is power. They will never allow cryptocurrency even if it got too many advantages compared to disadvantages because the government does not want something that they cannot control.