[fsflover]

Sell it to insurance companies, employers? Use it to target ads of snake oil to vulnerable people?

[simonw]

Sell what to insurance companies?

All they have is that there was a hit from an IP at a specific date and time. Any cookies they set will let them tell that the same browser came back an hour later - but won't let them join traffic together across multiple sites.

[fsflover]

IP can be correlated with other data to infer the identity. Google ads are everywhere, so Google probably knows, who you are and your IP.