Target ads but do not sell personal data and have thought out a nice architecture so your data stays at Google. They use a call back for the ad so a third party site does not get any data. Also why ad blockers work.
I never said they sold your personal data, I know they don't. But they still collect vast amounts of it that they use against you (advertising), and make available to governments if requested/ordered.
The byproduct is ad blockers work by blocking the call back.