It's amusing that after all this time and (hundreds of?) billions of dollars invested in adtech I still find the adverts in old magazines far more relevant and compelling than any of the "personalised" adverts of today. The industry as a whole has missed the forest for the trees by over-fitting their systems; I might be interested in the broader category, or a tangentially related one, but at no point do I want to see the exact same product I was looking at a day ago on every ad. I didn't buy it then for a reason, so I'm not buying it now.
Pervasive surveillance to make a system that's practically worse than the alternative that doesn't require mass surveillance, and is much simpler and cheaper. Did I say amusing before? Depressing is probably a better fit.