Ayn Rand very much did not believe that people are only rich or poor by their own merits, especially not in a world where people have various limits on how far they actually can rise. She especially focused on the artificial limits imposed by cultural and political beliefs and enshrined in types of purported morality that actually advise a person that her own life is of no matter and what is or isn't what she wishes or seeks in life is to be given up for what other's say she should seek or what others want.
She actually taught freedom to make your own choices and live by them and argued persuasively that when one has the freedom to do so that maximal happiness and flourishing is possible for oneself and for any culture/country that supports such.
Social Darwinism is far too simplistic in comparison.