Your question brings to mind the (possibly apocryphal) story about (IIRC) Target, who through the use of a customer's purchase history deduced that she was preg

Your question brings to mind the (possibly apocryphal) story about (IIRC) Target, who through the use of a customer's purchase history deduced that she was pregnant before she had informed her family. They sent targeted mailers to her house, leaving her father wondering why she was getting advertising for diapers and the like. I think the general public would care more if they got a better sense of what having a large volume of their seemingly innocuous data lets companies figure out about them.