I've seen a lot of statements from central banks from all over the world. Their logic can be explained by the fact that they are hardcore mainstream economists who were taught that it's their duty to protect the market from all sorts of risks and disasters with their regulations. They were also taught that fiat money is a superior system to historical systems like gold coins, barter, spontaneous money and banknotes backed by gold. So, in their eyes Bitcoin is a move back to unregulated money, which they believe is dangerous.
This just hits the nail on its head.