It's obviously bad when "real" data like full names and credit card info leaks, but most data companies collect is probably email address and some anonymous things like which buttons and when the user clicked.
Nevertheless, such data collection, tracking and telemetry is considered quite bad among power users. I don't support those practices either. But I'm struggling to consolidate my arguments agaist data collection. The one I'm confident about is effects on performance and battery life on mobile devices, but why else it's bad I'm not sure.
What are your arguments? Why is it bad when a company X knows what anonymous user Y did and made money on that info? What's the good response to anyone who asks why I'm doing the "privacy things"?