So, the scam here is from ad providers like google on anyone running ads. It's the reason that often you see ads for a product you just looked at forever: if you are shown an ad for a product, and then you buy that product, the ad provider gets a cut. If you click on the ad, that cut is higher. Now, clearly you already looked at the product without the ad, and at best it was a reminder of something you already wanted, but in the eyes of the contract, you bought that product because of the ad. That's WAY more of a sure thing than actually compiling a meaningful profile on the provider side. Now, on the opposite end, you DO have stories of storefronts sending out coupons, emails, direct to consumer ads, built on your viewing history on their site that ARE based on complex algorithms that know you better than yourself, which is how you get stories of the algorithm knowing people are pregnant before they do