People want to be connected, join social networks, download apps, be able to control their appliances from across the ocean, carry devices loaded with sensors everywhere they go--and on top of all it, they want privacy.
IIRC, that's what Apple is trying to do: they'll provide all kinds of cloud services, but in a way that they know as little as possible about the content beyond what's vital to providing the relevant service.
Apple is trying to sell hardware, which a robust encrypted cloud experience tied to that hardware will do.
Microsoft is trying to make money from the operating system; since they're giving it away for free, they have to sell commercial access to third parties (ads in the Start menu? really?).
Google, well, I assume they're out to mine as much data as possible, whether or not it's user-specific.
Not actually true. Windows 10 is not free, and Microsoft is not giving away the operating system.
What Microsoft is doing is giving consumers a free upgrade on Win7/8 PCs where the operating system has already been paid for.
This is basically the strategy already used by Apple and Google (Android): once you have bought the OS (bundled with the hardware) then you get updates free.
Except that Apple makes its money off hardware sales, and Google makes money off data mining ... for both, the operating system is just a means to an end, a cost center required to support the separate profit centers. Microsoft is, however, has the OS as its primary product.
These are fun and interesting times.