Comment by Terr_

Also the social-graph aspect.

For example, your aged mother's phone will get pinged within X meters of an urgent-care facility, or she'll do some web-search about "hip pain", and then all the adult children start getting ads about elderly-parent-care.

Or perhaps the pervy-panopticon decides some phone-on-wifi events look like adultery, and both suppposed spouses start getting ads for divorce lawyers, private investigators, or track-covering products. (Bonus if certain specialized "adult" toys are detected on Wifi or Bluetooth...)