That's not how money works.
Govt buying bitcoin is transferring wealth & influence & purchasing power to the army of cryptoanarchists that hold bitcoin. It accelerates the decline of fiat & removes the primary power that govt has in their effort to control society.
It ultimately removes their ability to print money. But it's so advantageous in the short run that govt officials will not do what is in their own long term best interest with regard to maintaining or expanding power & control.