Nothing says "Faith-based engineering" like buying a backup system you refuse to test.

I'd rank "not doing backups" pretty highly in terms of having misplaced faith in things not breaking, too.

I don't ask new Tarsnap users why they decided to start using it, but sometimes they volunteer the information; and by far the most common reason I hear is "I just lost all of my data, so I decided it was time to start doing backups". I am frustrated every time I see this...