Honestly confident alone cannot guarantee a success for your venture or business and worst you will try it again when you fail.  The most important thing in being an entrepreneur is knowledge.  It will be followed by skills and determination.  Confidence just push you to do something way beyond your capability which without proper knowledge and skill will more likely make you fail.
I admire people that write much about being successful, but believe me or not, most of them make it incomplete and make it appear to the reader that it is very easy.  They always put sugar coating in every thing they said that it almost hide the difficulties and hardship one must observe.