If you have the information the odds are that you are going to use it. Google have long time had both an advertising network and a lot of very personalized information. Up until recently the personal information have not been combined with the ad-serving.
“Google is the latest tech company to drop the longstanding wall between anonymous online ad tracking and user’s names”
Lessons learned? You can never be sure how your information will be used tomorrow if you are not the one in control thereof.