I feel like this is offensive on more than one level. The waste of our best minds... sure. Fine. But - "to sell you ads."
Marketting has the dubious distinction of being one area of human endeavor where technological advances serve mostly to make your life worse, make your mind less focused, make your wallet more empty.
The spherical-cow "ideal" 100% efficient perfect marketing campaign/tactic literally hypnotizes you into dropping all your money on an arbitrary good or service. It is isomorphic to somebody mugging you. What does it look like if we achieve 10% efficiency? 1%? How is this infringement on your agency and financial well-being a positive social good? What if we could achieve profitable returns even by flooding the zone at 0.001%? How many ads do you want to be subjected to per thing that somebody in your neighborhood buys?