It mostly about he control over the macroeconomics which keep those people afraid about the increasing adoption of Bitcoin a and other altcoins. For instance, let us assume that a country has a lot of adoption of Bitcoin and the government wanted to change the number of FIAT in circulation, adjust the interest rates on credit, sell debt, etc. Most of those things would not have the effect they would want it to have because an important percentage of the population would be isolated from whatever the Central Bank or the Treasury of the Stated wanted to do with the National currency.
That alone is enough tho keep bankers up at night.
This is exactly the reason and I believe that we shouldn't really worry about those governments because they are not going to do anything about bitcoin like banning it. Because if you ban bitcoin, there are millions of people in most nations that uses it and you risk not getting their votes, doesn't mean they will vote for the other person, maybe they would but they could just sit at home as well.
That's how most elections are won in the world, if you can make your voters go out and vote you win, if they protest and stay at home then you lose, it is usually not getting the vote of the other side, that doesn't happen too much. So, politicians would be worried that they would upset their own voters and not do anything about bitcoin.