In the context of the question:
Why is data collected?
It seems that our everyday lives are transformed intentionally (or unintentionally) into usable data; our social relations are mediated extensively by machines. Tech giants of Silicon Valley make adequate investments so that they can make use of all the data they store. Maybe what they possess is a goldmine. Can they establish a new model of sovereignty?
Who is listening to all of these views and information about our networked published selves? Who cares?
Indeed this vast amount of information is not garbage. There would be no reason to set up an infrastructure of this scale from the owner companies to host all this data if they were not useful. All these emissions are not wasted; there is some sense in all of them.
Now, let's imagine that I unashamedly start shouting my personal information, tastes and opinions in a public square. Would the state security assign an undercover police officer to take notes of all the information I share, expecting to grab any notorious details or dark secrets about my life? Or would a team of advertisers bother to collect my preferences as useful information for their next advertising campaign? I don’t think so. But what if this kind of information were coming from millions of people around the world, in the form of large-scale data? Probably that would make a difference.
The collection of a significant amount of social experience, stored as data and sliced into many small pieces, can be easily processed and analysed. One could argue that this entire collection has been placed voluntarily by people across the globe on the servers of some companies. And this collection is beneficial property; it is a collection of raw material derived from the stray productivity of free time.
Can we compare the power of big companies, to the power of the State? The State, composed by the ruling class, forms the ruling ideas, and can shape to some extent the wishes and desires of the citizens. Is it possible that giant corporations now have this kind of skill?