If you have not had an attack or at least an attempt, then it is probably just a matter of time. So what happens when you open that email and click on the link which activates a virus? Suddenly your files are encrypted and you have a ransom demand.

What do you do - call Microsoft? They will tell you  that there is no guarantee they can recover all (or any) of the files and if they can it may take some time (hours/days/weeks)

With a cloud backup solution - in a matter of minutes, you can recover the file (in fact all of your files) as it was before the virus hit.