“Such concerns didn’t strike me as farfetched, but I was reluctant to air them in mixed company. I knew that many of my fellow citizens took comfort in their own banality: You live a boring life and feel you have nothing to fear from those on high. But how could you anticipate the ways in which insights bred of spying might prove handy to some future regime? New tools have a way of breeding new abuses. Detailed logs of behaviors that I found tame—my Amazon purchases, my online comments, and even my meanderings through the physical world, collected by biometric scanners, say, or license-plate readers on police cars—might someday be read in a hundred different ways by powers whose purposes I couldn’t fathom now. They say you can quote the Bible to support almost any conceivable proposition, and I could only imagine the range of charges that selective looks at my data might render plausible.”
I don’t necessarily recommend becoming paranoid, but it’d be silly to continue walking around without recognizing how much of our behavior, especially online, is being monitored, recorded, and interpreted out of context. Right now it’s more likely that Apple, Google, Facebook etc., are using the information to push ads to you, but don’t discount how much government agencies are doing the same tracking, and potentially making decisions about you based solely on that information.
The article is a long read, but worth the time. Unless you want to continue living in blissful ignorance.