What is IDrive Online Backup used for?

I use it as an additional off-site backup for all the files on my laptop. I use OneDrive on a limited basis, out of concern that if they were hacked, I'd have no access to my data. My reasoning is that Microsoft is a more likely target due to their ubiquitous nature, whereas iDrive isn't as big a target.

The answer is more than simple. It's like a safety box in a bank. If a tragedy happens to you, like your computer being stolen. A fire at the residence which causes your computer to go through it, or a flood, tornado, etc. By purchasing a new computer equipment, you will be able to recover all your data. So, you will not have lost anything since your misfortune.