I can tell you exactly when the threshold was crossed for me. I'm pretty removed from the tech industry but many of my friends are in tech so I try to keep up. One day, I was searching for a photo of a jacket that I wanted to sell on eBay. Google images led me to a site called Tradesy which had a stock photo of the jacket. I clicked on it, it led me to an unrelated photo, so I clicked out of it. Immediately, I received an email in my personal/professional email box (not the email I use for website registration/spam/etc) inviting me to use Tradesy. To this day I have no idea how Tradesy or Criteo (who sent the email) got my personal email address from the simple act of my browsing to one page. An email I never enter anywhere, EVER. The violation I felt was so intense, I installed an additional ad blocker and blocked Tradesy. I have no idea if that helped but that was my moment.