I believe deep inside them, those people behind the Central Banks, they know that "the cat is out of the bag". Billions and billions of the paper money they print will shift into sound money, Bitcoin.
https://www.ecb.europa.eu/press/key/date/2020/html/ecb.sp200930~169abb1202.en.html
"We must explain much better to the general public what we are doing and why. Monetary policy can only be credible if we ensure that our goals are truly understood and shared by the people we serve".
I don't think so anyone is afraid of anything. There have been pretty tough times for the monetary systems in the past like the 2008 depression or the LIBOR fraud technically it makes no sense as the amount of people doubting the system aren't too much moreover these people opposing don't really have a plan or a complete system as a replacement. Just saying that bitcoin will be an alternative currency doesn't solves the issue of bringing the entire ecosystem on it. So as long as there is no completely robust idea for replacing the existing system. They aren't really afraid of anything.