I'll wager megabucks that of the hundreds of people that are reading this article only a scant few have backed up their hard disk drive in the last month.
Backups are insurance.
Insurance for you in case something happens to the computer's hard disk drive or the documents you have so meticulously created. You can always replace the computer or the hard disk. What you can't buy is the time you have spent typing documents or entering client billing data. The months and years of time cannot be recovered easily without a backup. Let me give you an example.