The best predictor of success or failure is the mindset, where attitudes are formed. Those who achieve great things generally believe they can improve and grow as people (Growth mindset) while those who are frustrated in their attempts to realize their dreams tend to believe their abilities and talents are static (fixed mindset). Having the belief that you are in control of your own ability, and can learn and improve is the key to success. Yes, hard work, effort, and persistence are all important, but not as important as having that underlying belief that you are in control of your own destiny.
Choosing to develop the right attitude and growth mindset ultimately leads to a mentality of being able to think/act without the help or influence of others and the ability to decide what you should be or do (Self-reliance) resulting in the discovery of various opportunities.