There are more reasons to quit Instagram than just the fear that they will be selling your photos to advertisers. From the Egg Freckles post What I Left Behind in 2012:
I know Instagram won’t be selling my photos to advertisers, but by introducing advertising on Instagram their intentions are clear. I was never meant to be their customer. Only their product. Starting in 2013 I only want to support companies that are proud to have me as a customer. Instagram may be a slick app for taking photos, applying filters, and sharing pictures with friends, but their are better ways to do all three on my iPhone. By not limiting myself to Instagram I have more options. My favorite filters won’t suddenly disappear. I can share my photos on App.net. And I can still follow all of my friends photos by visiting their public Instagram profile pages, or by clicking the links they post. As Instagram’s popularity increases more of the photos in its collection will be of blond teenage girls, fingernail polish, and guys with their shirts off. These are photos I don’t need to see, and the reasons why I won’t be missing Instagram on my Home Screen in 2013.
I personally thought about quitting after it became clear the service was no longer social-network neutral when it dropped support for Twitter Cards. I’m a sucker for being able to view images inline with a Twitter post, and not having to go out of my Twitter client to the web, which I now have to do to view Instagram photos.