Data like any other tool can be used for good or ill.
There is a lot of new advances in many areas of science that is coming from access to large annonymized data sets. More accurate health screening. Better predictions on wher a disease is spreading. Better traffic management. Better energy management. Better weather and climate predictions. On and on and on in ways we haven't even begun to imagine.
Can it be abused? Certainly as you say history has shown that. Of course since it is history it means not having access to this data hasn't done a damn thing to stop it. If anything I would suggest it is because we didn't have access to this sort of data that allowed these sort of abuses to happen.
I am sure you'd like to tell me about the evils of big government and big business. Fine that is want vigilence is for, to keep them in line and in check. For all the examples of abuses you can come up with take a moment to consider the actual world we live in and how much of it is shaped by that government and those businesses. Would you really want to give up things like electricity, modern food, modern medicine, communication, transportation, the Internet, etc, etc. Even our desitute have better lives because of the governement and businesses.
Yes it isn't a perfect world. There is a lot that still needs improving and made more efficient. We have a big problem in distribution. In a lot of areas we have more than plenty to support everyone. What we don't have is ways of being able to efficiently distribute those resources. It isn't even a matter of greed, just that it simply isn't sustainably feasible to try and do so. A lot of those answers are going to come from studying the private data that is being gathered by the multitude of sources.
Does this mean we have to give up complete privacy? I don't believe so. Nor is my point to convince you to use Google or even take off your tinfoil hat. My point is for all the fear you have of what could happen and trying to hide from it, the world is becoming a better place by what is happening. Fear of tyranny is tyranny itself. The answer isn't to grab our guns and lock ourselves away in a bunker (although that would be the only way you get true privacy) but to be vigilant and hold companies and government responsible to do lets say the better things and minimize the worst.
Try and consider the potential good, for you personally and for society with as much weight as you consider the potential bad (granted we actually aren't wired to do that well, but try anyway).