We've all heard someone ask: “Who are you to judge me?” or some variant of that question. It's a defensive question usually asked by someone who reasonably expects to be judges harshly by their peers for some ethical or moral transgression. It's safe to say that someone secure in the notion that society or their peers would judge their actions favorably, is not going to pose this rhetorical question. A good retort to that question might be: “Who are you that you are above judgment?”
When we base rights on what is good for society, that begs the question: Who speaks for society? Throughout history, such people who claim to speak for society inevitably turn out to be tyrants. You have a few, even a single person, deciding what is good for the people. Rand thought that people ought to decide for themselves, based upon rational self-interest.