We all know the influence that propaganda has on an entire population - we've seen what happened in Germany in WWII and in South Africa during Apartheid, and it keeps happening all the time. Withholding certain information and releasing other information through mass media can influence how a country thinks and ultimately votes (any country).
I lived through Apartheid and saw first hand how pursuing what was thought to be (we were told) illegal posters being put up on poles, was in fact (I later found out years later) actually put up by another government entity in disguise pretending to be a different party. The exercise was clearly designed to activate defence mechanisms and patriotism within some of the security forces, much like a country goes to war and buries their internal differences to face a "common enemy". South Africa was constantly told it was under "total onslaught" by external communist forces and no counterviews were reaching the general population. Targeted propaganda is a real thing.
So when data is collected from individuals en masse that exploit their fears, doubts and hopes, and then targeted propaganda is then focussed on pushing the buttons to get reactions, it can be a very dangerous and real issue. Fake news is very real and it can be weaponised to change the way people think.
It's not new and it's not going to go away - awareness may be our best defence. In many cases, it is social media and news media that is manipulated (knowingly and / or unknowingly through adverts) but often they are also the same means to expose such behaviour... its a bit of a Catch-22.
One interesting statement in the documentary was - the value of tech data has surpassed that of Big Oil. It's not only that money value but also the power it can wield. Such power can be used for evil or for good but who gets to decide or judge that?
See the trailer at #^https://youtu.be/iX8GxLP1FHo
They took your data. Then they took control. The Great Hack uncovers the dark world of data exploitation through the compelling personal journeys of players ...