Frustrated

Why is it when you offer extra credit to help raise kids grades it is always the ones who really don't need it because they already have an A in the class? I don't offer extra credit that often but when I do, it is rare that anyone takes advantage of it (except for the kids with the 100% already). Free points and no one takes advantage of it. I consider it frustrating that I am trying to help them and yet they won't help themselves. UUGGHH!!!