True Self-confidence IS Self-knowing, but very few people have any real idea as to who they are. Most of us identify with an ammalgam of self-generated self-images. We play a host of roles, some it which we are seemingly confident (generally if we're competent in those areas) and others in which we have little confidence. Try leaving a job-role your familiar with and going into a completely different line of work - perhaps even in a different country - if you want to test this confidence thing out for yourself.
And what is success? There are many definitions. A very commonly held believe is that fame and fortune are a measure of success. But a great many famous and very rich people are absolutely miserable with their lot. Is this success?
Think carefully on Self-confidence and Success. It is very likely that not only will your views on both change - you will change along with them.