For everyone who reads this and thinks "Why should I care if they know what products I buy? That just means they can better deliver ads that I actually want to see!" needs to realize one thing.
They all share information with each other. The information that is collected is used to make decisions that most people cannot fathom. The example I have is related to online tracking (using cookies and web beacons). There are companies RIGHT NOW that collect data about you from all of the sites that you visit and sell that data to banks. Your browsing history can impact your ability to get a loan. It can impact your credit card interest. This isn't hypothetical, it's happening. The worst part is that the patterns and correlations aren't "logical" to us - it's all done by algorithms. You going to a toy store could impact your car insurance rates - that doesn't make sense to us, but if the algo determines that it's true, it's going to be used that way against you.
Tracking your behavior and patterns will be used to make companies money, whatever that takes. That's all this is about - your identity being bought and sold so that you can be milked for more money in any way possible. Your privacy means ZERO.
They combine your browsing history, phone tracking, etc across multiple platforms to know what you do and how you do it. It's done using complex methods that humans can't even comprehend.
There's another that I can't find at the moment that has determined that how you answer "fun quiz!" popups is an indicator of your credit worthiness. How you answer those questions can cost you thousands or even tens of thousands of dollars in the long run! Again, not tinfoil hat stuff - this happens today.
I stress that it's not any 1 thing that they collect that can be used against you. They are tracking everything you do on every device - down to tiny details like how long your cursor hovers over a button before clicking. They gather information better than someone standing over your shoulder watching you all day. They know you, as a consumer, better than anyone else.
If that isn't scary, I don't know what is.