Here are some simple facts for you” Yes, Google, especially if you use a lot of their services, such as Google Docs, Gmail or Google+ knows a lot about you. If you just search a lot on Google, Google knows a good deal about what interests you. So what! It’s been that way since day one. If you use any Internet service or Web site a lot they know a lot about you.
How do most “free” Web sites pay for themselves? With advertising. How do they know what to advertise to you? By watching what interests you. Google does it. Microsoft does it. Everyone does it.