What you have in the Cloud is another copy of your data, which is good, but Microsoft is not backing up your data. What happens to all the data if a hacker got into Microsoft and was able to delete the data held and synced by OneDrive? Because OneDrive, is a bidirectional synch, I believe that data would be gone off OneDrive, and off your PC!
back up computer
Computer makers are turning encryption on at the DOS level in the operation system. When a consumer goes to see if encryption is on or not, Windows settings indicate that the drive is not encrypted. But it really is encrypted at the DOS level. Why should you care? This makes retrieval of files all but impossible if you have a computer failure and no backup.