In many countries there is no money. They are in debt. What exactly can they invest? Who will risk the money of the budget? Why don't you think that bitcoin was invented by the American intelligence agencies to collect the inflation dollars from around the world and then bankrupt bitcoin? As you are such a conspiracy theory?
This is quite true! A lot of the countries are in debt depending on the unions with the countries they are with. Take in an example the EU. A lot of the countries have entered into it and now are struggling towards tracking the progress of this same alliance. They must borrow the money from the EU representatives that are in control of the financial asset to achieve the requirements for staying in the EU.
Bitcoin, even if can turn the tides around and help the country in some way by my opinion, is very risky move and even if the country would invest into decentralized currency they would have to elaborate their actions to the representatives of the EU and to other countries. Money cannot disappear just like that and I think that the most countries wouldn't approve such actions.