Yeah sometimes the Princess Auto ads chide, saying "that project's not going to finish itself". I think the inference being I need to visit them again, buy more tools. Project's long done, lol.
I suspect this is more about the advertisers buying lists only of people searching for those generic product classes, and not paying extra for the lists of those who actually bought product (to weed out of targeting). If their surveillance suppliers even have the latter. The big data surveillance sellers would most certainly charge extra for more finely curated lists of prospects who searched but haven't yet bought, quite possibly more than the wasted cost of sending ads to those already off the market.