The price differential between buying the hw/sw & staffing a professional (or team of professionals) to curate and maintain it 24/7/365, or simply off-loading it all to an outside party, could be huge -- I'd dare say huge enough to make or break a company. From an executive POV, why care about data safety, when hosting it yourself makes your business model non-viable?
I realize there are lots of problems with this line of thinking, and I'm not advocating it at all, but I'm willing to bet this has been the case for some.