Or even that I primarily spend my money on Amazon when actually buying something.
It's my feeling that for the majority of people their browsing data will rarely translate to direct sales.
Our unencrypted database was compromised and all your browsing history and our analysis of your daily habits is now on sale on blabnlablabla.onion/sell.php?product=123 starting from 0.002BTC per year of history of a user.
Or to make attribution easier for multiple devices in the same household?
Both of those make ad spending more efficient, which translates directly into better revenue for companies buying ads.
Or inversely, if you use FB a lot, FB shouldn't advertise to you as much
But it's "dumb" targeted advertising; it's nearly always for the exact things I've been browsing lately, or things that I've bought lately.