I worked in an Ad-tech start-up in Berlin run by two of the most evil f*kers I've ever encountered. I built out their principal ad auction algorithm and a lot of the back-end to support it, and all they did with it was target vulnerable groups of people at particular times of the week when they thought they were at their lowest ebb.

One meeting in particular really stands out still, a social media giant that everyone knows was in town meeting the founders to sell additional personalization data. Before that meeting, I thought things the start-up were doing were a bit sketchy, maybe borderline unethical. During the meeting itself, it was more like sitting around a table with Dr. Evil and a few henchmen. They were actively, unambiguously picking vulnerable groups for ad re-targeting. And that's not even the worst of it, the meeting wraps up and one of the founders says "OK guys, let's go get some beers and bring some girls". Then this despicable excuse for a man promptly walked out into the office, points at a few female employees and says "You, you and you, come with us now".