A digital dollar is incredibly dangerous. It would threaten to eliminate the physical dollar, making it easier for the government to track purchases. Not only this, but money could be endlessly printed without the inherent limitation of physical money (e.g. number of printers, workers, cost of operation). If the digital dollar was built separately in the fashion of bitcoin where there is a finite number of bitcoins and the blockchain prevents shenanigans, it might work, but when has the government not been incompetent except when collecting taxes. Even that's debatable.