The attitude of confidence forces a normal human to become a leader, achiever and more powerful than that. It pushes a person to climb a ladder called success; it makes rags to become rich.
As Jesus sent His disciples out into a world that would be hostile to them, that would imprison them and beat them and kill them, what they needed to succeed wasn't a new car, or perfect teeth or a retirement plan. What they needed to live successfully (as God defines it) was The Comforter.