Windows 10 is basically free considering it comes on $100 tablets now, and you can easily buy OEM win10 home licenses on eBay for $6. And the fact that they upgraded all win7 users to win10 for "free". Microsoft expects to make money from office365 subscriptions, xbox game store purchases, azure, etc.
I find it so frustrating when people trot out the "if you're no the customer, you're the product" about Android and then claim that it's impossible for Apple to monetize your data just because you also paid through the nose for that shiny iPhone.
If you're paying for a product, you are the product, too. Merchants, banks, credit card companies, utilities, etc, routinely sell your transaction info up the river.