I don't have a problem with ads, per se. I don't have a problem with billboards or magazine ads or little league team sponsorships. Hell, I run them myself at a local club.
What I have a problem with is the type of targeted advertising that depends on collecting data about my every click, location, and thought. The type of data that is used to profile me to such a degree that they know more about me than my closest confidants and even than I do about myself. It's just fucking insane. And it's just so wildly profitable that almost every piece of software is doing it.