> I think it's way better to shop at a bookstore filled exclusively with stuff you've already shown interest in
That sounds like quite the endorsement for targeted advertising. In a good way - really I would love targeted advertising if it were implemented differently.
Pretty well-established that targeted advertising works better than untargeted advertising, all other things being equal.
I think you should put things in your bookshelf or collection of pdfs to hold off FOMO. When you finally get back around to being interested in Bosnian history, the books you wanted might be impossible to get. If you never get back around to it, you can help some stranger out who did.
I guess this is becoming less true with the libgens and annas-archives of the world, but when those all disappear on the same day (that seemed like any other), you'll have missed out. I certainly don't miss the days when I spent years waiting for a book to come up on ebay or used.addall.com at a price under $150.
Targeted ads are great, when it's actually consumer focused. Sadly the nature of modern ads makes it so all the power is taken from the consumer. A proper targeted ad should have the ability to say to it "I never want to see yo again", and virtually no advert would ever want that to happen.