"...I think its too late for the ad model.
The ad model left the building years ago, it moved into the spy model a decade or so ago. Most of the money is being made from spying on citizens, seriously...
This is how it currently works (sadly)...
--- daily citizen harvest: entry #1 -----
1a. You're phone just reported that you're inside a doctor's office.
1b. You're credit card just reported you're inside a doctor''s office.
1c. You're insurance provider just reported you're inside a doctor's office.
1d. You're doctor's office just reported you're inside a doctor's office (yep :-/).
2. Gather all information on patient and office then anonymize or "accidentally" forget to anonymize the data and send it to corporations X, Y, and Z.
--- daily citizen harvest: entry #2 -----
1a. You're phone just reported you're inside a grocery store.
1b.....
It's a pure spy game, this fact cannot be danced around.