"Many people have a combination," said Dweck. "Oprah may not be in it for the fame and power and she may be in it for helping people and growing her own personal qualities. But the fame and power gives her the leverage to fulfill her mission."
And while it may seem like Winfrey has the magic touch, the secret behind her ambition and success isn't actually all that secret.
Dweck says that the amount of hard work a person dedicates to their cause determines how successful they become. Just being Oprah isn't enough, she said.
While many experts attribute ambition to genetics, the history of ambition is more complex.
The late behavioral psychologist Dr. David McClelland, long affiliated with Harvard University, explained ambition and success by analyzing early childhood experiences.
According to Angela Duckworth, an assistant professor at the Department of Psychology at the University of Pennsylvania familiar with his work, McClelland believed that ambition stemmed from a deep unconscious drive. Kids who were more independent and whose parents demanded a lot from them tended to be more ambitious in the long run.
"Someone like Oprah with her success could have given up a long time ago and lived the good life," said Dr. Joseph Renzulli, the director of the National Research Center on the Gifted and Talented. "But I think that she has this mission that is trying to make the world a better place.
It's this mission that makes ambitious people almost incapable of being satisfied.
"As soon as they accomplish something they want to accomplish the next best thing," said Gartner. "There is a tendency to move the goal posts and to expand the sphere of their ambition to a point where it's overly grandiose."
"There is no stopping point," Dweck agreed. "You can always help more people and if you have a passion for what you do that feeds on itself. And if you want fame and fortune to prove yourself that doesn't end either."