Targeted ads are a myth. A myth used to sell Big Data surveillance to us schmucks. "Gives us insight into who you are and in exchange get advertisements for stuff that you want!"
The reality is that "targeting" ads with that kind of precision would require a full-blown AI simulation of your personality that is constantly updated with every new experience that happens to you. Which is obviously impossible.
Instead, Big Data is about manipulation its about figuring out what buttons to press in order to push consumers into spending money with the companies paying for the advertising. Most advertising is just about getting their client's name in the back of people's heads so that when they are ready to make a purchase, subconsciously the client's product is the first one the consumer thinks of. They want to be at the "top of the list" because few people have time to consider a list of more than two or three choices. That's how Amazon Prime (and Costco, etc) all work. But that's just the most benign form of manipulation.
There are lots of ways to be more manipulative. For example, they don't just want to show you ads for beer, they want to show you ads for beer with sexy models that are your "type." Or showing new parents ads for diapers with models that look like their family (e.g. showing white single mothers advertisements with white babies and a single mother happily doing it all on their own).
More nefariously, if you are prone to conspiracy theories, then they will show you political ads that play on your conspiracy theories. Or even darker, since alcoholism has a significant genetic component, they can send coupons to people with alcoholics in their family.