I never click on any ads (beyond the google ad that usually corresponds to google's top result), I never bought anything from ads. I usually use an ad blocker to not see ads.
Is there a point where the ad optimization algorithm is going to figure out that it's losing money chasing me?
If you use Gmail, you're being scanned in aggregate but busting individuals out of aggregates is .. triangulation.
How many 59 year old like me lie behind my ISP.. two or three extra measures and they can cross correlate to your visa card.
(Your card usage is being sold by everyone, bank and shop both)
Very probably the ad blocker only makes you more visible
Your browser string isn't the only way your identity is being checked online. Capabilities exchange identify os, all kinds of things.