In my opinion, the reason why a person fails to have a great career is more on intrinsic. But what if you are born in a native tribe in the Philippines? What if you are just part of the indegenous aeta in Benguet? Will you blame yourself or your native culture for not having a great career.
What if you are part of God's masterplan - that whatever you do, even you do the best of your very best, God planned that you will be forever a Bus driver? You cannot do anything if God wills it, isn't it? And that is if you believe in God.
But there's one thing I believe is 100% true...."fortune favors the bold". If you're bold enough or courageous enough to do your passion, chances are you will be successful in your career, am I right?