How do companies that offer FREE cloud storage make money???

Lest we get too paranoid , Keep in mind your "personal information" isn't your specific Data. its info about you and your habits demographic info so that ads can be targeted to people most likely to respond ( and thus they can charge a higher rate ) Storage is normally cheap so it a good way to get you hooked on their products , Apple . And especially Google comes to mind as providing services that keep you close to them.