Thinking you know all there is to know probably won’t get you far. Arrogance and a certain reluctance or unwillingness towards learning are lousy character traits for entrepreneurs.
Confidence, on the other hand, is an absolute must. Failing repeatedly and climbing back up requires a special kind of superpower. Without it, launching or running a business proves to be a rather substantial pain in the neck.
Finding that perfect balance between humility and confidence is a lifelong quest.