As we get tracked more, algorithms will start making better predictions about us. The negative side of this is that you will get offered ads that are specifically tailored to your interests, at the time you are most likely to buy at a price point you can afford. Essentially you will get controlled and primed by machines to consume, feel certain ways, agree with certain sentiments etc. That's not the kind of dystopia I want to be in.
This is already happening, Facebook has done experiments about user emotions. https://www.forbes.com/sites/kashmirhill/2014/06/28/facebook...
Youtube is using machine learning algorithms for suggesting videos https://static.googleusercontent.com/media/research.google.c...
There is nothing to stop a company from manipulating user emotions enough to guide you down the path of buying a product.