I do not have a Facebook account. Not sure that this matters a whole lot anymore from a data collection standpoint (see here and here). However I saw some interesting articles on the actual use of many of those quizzes that get passed around. You know the ones... "What Simpsons character are you" and the like.
Well many of these come from Cambridge Analytica. They "use data modeling and psychographic profiling to grow audiences, identify key influencers, and connect with people in ways that move them to action." Companies like these are able to capture that data from the quiz and build psychological profiles. That on top of the data Facebook already has and shares about you allows them to build highly useful datasets to advertisers and companies.
People needing ads get the nice benefit that they can be hyper focused on a specific market. However as Forbes recently found out, certain people running for office can pin-point target a voter base and drastically swing political opinion.
Politics aside, this is brilliant. One of the many reasons that I think big data, data analytics, machine learning, and other data processing tools will be the big players in shaping technology moving forward.