An excellent point:
When you stand and petulantly demand some course of action without regard for the bigger picture, you immediately place yourself into a tiny little box. This person doesn’t understand the full scope of what he is asking, so I can disregard this particular request. Sure, you might know what you are talking about (might even be right in absolution), but the fact that you present your case in isolation makes it less compelling to the person you are trying to influence.
Instead of just taking the free ice cream, try a simple acknowledgment of the associated costs. By placing your request in context, you do a couple of things. First, you demonstrate that you are informed, which lends your position more weight. Second, you highlight that you understand the other person’s position, which helps build rapport. And finally, you open up a conversation about costs and tradeoffs, which is typically the core of the problem in the first place.
What are you demanding from others without regard to what it will cost them? Is that why you’re not getting results?