It seems that the majority of Big Data/Data Science applications are designed to give advertisers insight into things I don't really want them to have insight into. That really sucks, because the technology is cool, but I don't want to help build that kind of future. It's kind of analogous to how I feel about Computer Vision: there are a handful of legitimate purposes for it, but most applications of the technology fall somewhere between "I don't like that idea" to "that's totally unethical".