I think you underestimate the amount of information google learns from your email. What you bought, where you bought it, how much you paid, which emails result

I think you underestimate the amount of information google learns from your email. What you bought, where you bought it, how much you paid, which emails result in a sale conversion, who you talk to, services you subscribe to, political affiliation, job status, career field, charitable giving, hobbies, and vices. By using a Gmail account you willingly tell others to send information about you to Google.