Some examples of what I'm fine with: if I visit a hardware store's online website and am then retargeted by their ads, or I visit a hardware magazine's website and am then targeted by hardware ads.
How so? Ad tech wants to eat as much of your data as possible. They’ll use everything they have to make inferences about things you want, things you believe, things you might believe later. I think you could go as far as saying they want ALL your data and then some..
The site showing an ad knows the context of what I'm looking at, whether that's a specific news article or the weather. That's enough info for a reasonably targeted ad without needing to match back to my browsing history, who I bank with, my likely religious views or sexual orientation, etc