I don't have a problem with the goal, which is to reduce fraud. The problem that I have with "big data" is that it shifts the balance of power. By destroying privacy, individuals become powerless to do crime (that's good) but also to organize secretly to work for social or political or economic change (that's bad).
We end up with utterly powerless men who have huge gun collections and ride motorcycles or drive obscenely large trucks in order to avoid confronting the reality that they are powerless at home, powerless at work, powerless in their local communities, powerless against their local government, and powerless in general society, including all of the concentrations of power at that level of aggregation: big government, big corporations, big unions, and big propoganda (I won't call it "media" or "news" or anything other than what it is.)
The issue is that the powerlessness of the individual is an existential threat to the survival of Western cultural notions of liberty, justice, individual responsibility and empowerment, sovereignty of the people, and self government.
The nice thing about "Big Data" is that nobody is forcing you to leave any information about you or your loved ones. Everything you do is voluntairy. Now, as long all sides of the contract (e.g Facebook) holds the terms that are stated in the contract I see no problem, if they donæt then it is a problem but it is not related to Big Data, it is related to morality of humans.
I feel like "Big Data" has become a big buzz word that many people are afraid of. Big Data is in reality a big statistical survey that may be used for both good and evil. What you described, company A giving your credentials to company B has nothing to do with Big Data. Big Data consists of calculating and analysing terabytes and petabates of data. And yes, even you can do it on usual COSTs. Industry standard software is open source and prette easy to use.
Yes, we are using the term "big data" differently. I'm not opposed to your enthusiam regarding the emergence of technology that enables society to know enough about every individual on the planet to (1) locate them and (2) profile them psychologically. Capabilities per se are exciting. But technologists often end their inquiry there, often because they make their living by developing technology. But the inquiry must not end there.
Does it really not concern you that there is now no place to hide? Responding that you have nothing to hide is not adequate, because exercising freedom often requires defense of freedom, and defending freedom might well require secret acts by many individuals.
If technology has eliminated the ability of individuals to defend their freedom, such freedom as they currently have will not endure for long.