The million dollar question.
Should I be spending money on backing up my Office 365 tenant.
What even does this mean?
Office 365 is the umbrella to many apps that can run independently of each other whilst also being tightly interlinked.
You can backup Exchange mailboxes, Sharepoint content, if you wish.
Or you could use a combination of recycle bins & rentention policies.
The rest of the apps is a minefield.
Dependencies, APIs don’t exist etc.
How would it work in reality even if they did?
Tony Redmond does a great job of covering the key points here.
Office 365 back solutions don’t exist.
Well not in they way you were probably envisaging.