Here are 10 inspiring lessons you can learn from their journeys to the top.
"Dreaming is one of humanity's greatest gifts; it champions aspiration, spurs innovation, leads to change, and propels the world forward," says Branson, in a blog post published earlier this year. "In a world without dreams there would be no art, no adventure, no moon landing, no female CEOs, and no civil rights. "What a half-lived and tragic existence we would have."
"The benefits of dreaming far outweigh the perceived risks, because the value of dreaming isn't just measured by the outcome, but the inspiration that comes from journey of achieving the dream."
When Facebook launched the News Feed feature in 2006, protesters demanded that the social networking site return to its earlier state. Zuckerberg is proud of his team for not caving to popular opinion.
"One of the things I'm most proud of about Facebook is that we believe things can always be better, and we're willing to make big bets if we think it will help our community over the long term," writes the CEO. "News Feed has been one of the big bets we've made in the past 10 years that has shaped our community and the whole internet the most."
When Branson wrote about the closing of the Virgin American brand, he celebrated the process of building the airline: "This was the ride and love of a lifetime. I feel very lucky to have been on it with all of you."
Jobs had a reputation for being ruthless, but Kara Swisher, the executive editor of Recode, says that was a result of his obsession with perfection.
"People used to say he was heartless," says Swisher, talking to Tim Ferriss, author of "Tools of Titans" and "The 4-Hour Workweek," on his podcast, "The Tim Ferriss Show." She sees it differently: "I think he had too much heart. You know what I mean? He cared too much. He had so much heart that he just couldn't stand it when things weren't right."
"The benefits of dreaming far outweigh the perceived risks."
After emotionally sensitive user content was removed by the Facebook content regulation algorithm earlier this year, Zuckerberg apologized publicly.
"We've seen this in misclassifying hate speech in political debates in both directions — taking down accounts and content that should be left up and leaving up content that was hateful and should be taken down," says Zuckerberg on his Facebook account. "This has been painful for me, because I often agree with those criticizing us that we're making mistakes."
"The barrier to change is not too little caring; it is too much complexity. To turn caring into action, we need to see a problem, see a solution, and see the impact. But complexity blocks all three steps," the co-founder of Microsoft said in his 2007 Harvard commencement address.
"Finding solutions is essential if we want to make the most of our caring," Gates said. "If we have clear and proven answers anytime an organization or individual asks, 'How can I help?,' then we can get action and we can make sure that none of the caring in the world is wasted. But complexity makes it hard to mark a path of action for everyone who cares, and that makes it hard for their caring to matter."
@Harvard: Mark: They know we didn't actually graduate, right? Bill: Oh, that is the best part! They actually give you a degree! #Harvard17
"He had a focus that was unlike any other," says Tim Cook, as explanation for why Steve Jobs was the person who influenced him most. What allowed the legendary CEO of Apple to focus so intently was his ability to prioritize, says Cook: "His thinking was so pure. He wasn't trying to maximize his wealth, or anything else."
The co-founder of Paul Mitchell hair products and Patron Tequila is a billionaire now, but early on in his life, he was homeless and collecting cans for money.
His best advice for entrepreneurs is to build a business in an industry that doesn't require lots of persuading buyers. Instead, he seeks out products or services that will become part of a customer's routine.
"You don't want to be in the selling business," DeJoria says. Instead, you want to be in the reorder business, where "your product or service is so good, people want to reorder it or reuse it."
Branson has four young grandchildren, three toddlers and one newborn, he says in a blog post. "I've been thinking a lot about the meaning of life and about the things that I want to teach them so that they live the best life possible," Branson says.
The Virgin founder and chairman says he keeps coming back to a quote from the children's book "Happy Birthday to You!" by Dr. Seuss: "Today you are You, that is truer than true. There is no one alive who is You-er than You!"
Branson suffers from dyslexia. He has had to learn to embrace his uniqueness, rather than allow it to be an impediment. "Yourself is always the best version of you — and being yourself is among the best advice I have ever received," says Branson.
"My mother, who was filled with pride the day I was admitted here, never stopped pressing me to do more for others," Gates told the Harvard graduating class. "A few days before my wedding, she hosted a bridal event at which she read aloud a letter about marriage that she had written to Melinda. My mother was very ill with cancer at the time, but she saw one more opportunity to deliver her message, and at the close of the letter she said, 'From those to whom much is given, much is expected.'"
Gates listened to his mother. He is one of the founding members of The Giving Pledge, through which wealthy individuals commit to donating more than half of their fortunes. He is also the co-founder of the Bill and Melinda Gates Foundation, which works to lift children out of extreme poverty.