If you post pictures online, there is always fine print to wade through to determine who has rights to what and protect where your images can end up. Some people post with wild abandon. Others go to great lengths to make sure their images are fully in their control. So to people in the second camp, today's announcement from Instagram about it's new terms of service probably does not come as a shock. The long and the short of it - they can use any image posted on the service for any purpose, as in, Instagram can get paid by an advertiser to use your image, and you will not be compensated or even asked.
This article from wired.com outlines the terms and tells you how to delete your account, should you decide choosing which filter best suits your plate of scrambled eggs was too much stress anyway.