If people are truly self-confident, why would they try to debate you on whether self-confidence exists or not?
It depends on how you define self-confidence. I like to think I've become a lot more confident recently. I have shed and/or quieted that nagging doubt voice quite a bit. I've gotten pretty quick at catching myself if I start thinking negatively. I walk taller, am not afraid to say what's on my mind and am generally not afraid of "what other people will think". I'm also confident that I have the ability to achieve my goals, even the ones which I can't quite see the path to, or the ones that seem outta this world and impossible.
How I gained self-confidence, I talk about in anoither thread about htis topic.