Most everyone that says that they don't care what others think of them are just kidding themselves...you may SAY that, but deep down you do care.
I certainly care about what others think of me; I'm very shy and have very little self-confidence and it doesn't take much for someone to put me down (and trust me, people do it a lot). But I try to not let this bother. Not caring about what others think and not letting what others think bother you are two totally different things.