That's mostly true (except as another comment says, the "sell" and "buy" are backwards). Certainly the central bank can create as much inflation as it wants, b

That's mostly true (except as another comment says, the "sell" and "buy" are backwards). Certainly the central bank can create as much inflation as it wants, by simply printing and distributing more money (which usually takes the form of the central bank buying assets such as bonds with the new money). There's no limit to the ability of the central bank to make the currency valueless. In the other direction, they can usually increase the value of money (ie, create deflation) by reducing the money supply, but it is possible that at some point the public might simply stop regarding the government's money as being worth anything. The only thing that might stop that is that people would still need government money to pay taxes.