For whose benefit are you saying that?

I mean, suppose for the sake of argument that you really were a worthless useless person taking up space. Even then, what would be the point of saying so -- instead of, for instance, "So you think I'm a worthless useless person taking up space, do you?" [reaches for six-gun] "Prove it, mother****er!"

I'm not saying that one way is better than the other -- just wondering how you happened to settle on that one.