You need it. You know you do!
This section is going to be a bit of a rant. You’ve been warned!
Backups protect you against faulty hardware.
Source Version Control protects you against faulty developers.
Most people will endorse these two statements. We all know why the Challenger crashed, and we all know that the I in RAID stands for Inexpensive. And you might not believe this, but take the word of an ex-storage manager (me), the disks in your home PC are exactly the same ones that you can find in those very expensive storage arrays from EMC^2, Hitachi, HP, IBM, and so on, exactly the same (even interchangeable if you replace the casing). Did you ever wonder why those arrays have up to 10 spare disks inside and why your company had to install a revolving door (and issue an access-at-all-times badge) for the storage technician replacing faulty disks?
And yet, how many of you have a decent (regular, incremental) backup of your home PC? It does, in this digital era, contain all photographs of your loved ones, your tax forms, your bank statements, and so on. Are those not important, then?
And yet, we all know that the better class of developer sometimes likes to ride his/her horse tangent off into some unknown direction. This is allowed (and often encouraged in the more successful companies, because although nine-tenths of it will be a useless exercise, the one-tenth pays the whole company for a year), but is it not ...