It might be simply driven by statistics, or as a human-directed strategy. While it seems counter-intuitive to the person who is targeted; (examples abound) - i

It might be simply driven by statistics, or as a human-directed strategy. While it seems counter-intuitive to the person who is targeted; (examples abound) - if you think about it from the perspective of someone selling widgets, the (set of people who are in the market for widgets) will necessarily include people who just bought one. Maybe they are not satisfied with their purchase? Maybe they want to buy another? Maybe they bought one, and it arrived damaged? Personally, I would think that this kind of "trying to think FOR me" is rather offensive to a lot of people, and probably turns-off a fair amount of people who are subject to it. On the other hand, it is probably true that people exposed to an ad for a widget, immediately after buying one, are statistically more likely to buy another. So as long as that is true (if it is) - then that's going to be a criteria for ad targeting.