I would gladly pay some yearly fee to be able to use Instagram (and most of the services I use often, really) ad-free. I really wish this was an option.

I assume either a) it's prohibitively expensive to implement such an ability based on how much revenue they expect vs. lost ad revenue vs. lower user engagement due to ads lessening the user experience, b) people are less willing to pay to put ads on your service at a given price if there is a segment of your user base that is guaranteed not to see them.