Mark Zuckerberg: 22
The Facebook cofounder and CEO became a millionaire in 2006 at age 22.
It didn't take long for him to make the leap from self-made millionaire to billionaire. At the age of 23, Facebook's IPO made Zuckerberg the youngest self-made billionaire in history.
Today's estimated net worth: $43.9 billion
Evan Spiegel: 23
The Snapchat cofounder and CEO became a millionaire in 2013 at age 23.
Two years later, the value in his Snapchat shares reached $1 billion, making him a 25-year-old self-made billionaire.
Today's estimated net worth: $2.1 billion
Sir Richard Branson: 23
Britain's high-profile billionaire earned his first million in 1973 at age 23.
Nearly two decades later, the Virgin Group founder reached self-made-billionaire status at age 41.
Today's estimated net worth: $5.1 billion
Carlos Slim: 25
The Telecom magnate became a self-made millionaire in 1965 at age 25, thanks to real-estate investments.
About 25 years later, his net worth passed $1 billion at age 51, and today, he is the second-richest person in the world.
Today's estimated net worth: $50.1 billion
Larry Page: 25
Google's cofounder earned his first million in 1999 at age 25.
The company's IPO in 2004 sent his net worth over $1 billion, making him a self-made billionaire at age 30.
Today's estimated net worth: $35.1 billion
Bill Gates: 26
Microsoft's cofounder became a self-made millionaire in 1981 at age 26, thanks to Microsoft's IPO.
The value in his shares surpassed $1 billion by the time he was 31, making him the youngest billionaire ever at the time. Today,Gates is the richest man in the world.
Today's estimated net worth: $74.7 billion
Elon Musk: 27
The cofounder of PayPal and Tesla Motors and founder of SpaceX reached self-made-millionaire status in 1999 at age 27 when he sold a web-software company for over $300 million.
By age 41, his net worth had surpassed $1 billion.
Today's estimated net worth: $10.8 billion
Sara Blakely: 29
It only took one year of running her company, Spanx, before Blakely became a millionaire in 2000 at age 29.
A little over a decade later, she became the youngest self-made woman billionaire at age 41.
Today's estimated net worth: $1 billion
Warren Buffett: 30
The investing legend and CEO of Berkshire Hathaway became a millionaire in 1960 at age 30.
He reached self-made-billionaire status by age 56 and is currently the third-richest man in the world.
Today's estimated net worth: $60.1 billion
Mark Cuban: 32
The "Shark Tank" investor and Dallas Mavericks owner became a millionaire in 1990 at age 32, when he sold his first company, MicroSolutions.
Less than 10 years later, he sold his second company, Broadcast.com, and became a self-made billionaire at age 40.
Today's estimated net worth: $3 billion
Oprah Winfrey: 32
The media mogul and queen of daytime television became a self-made millionaire in 1986 at age 32. In 2003, she became the first black woman billionaire in history at age 49.
Today's estimated net worth: $3 billion
Zhou Qunfei: 33
The founder of Lens Technology became a self-made millionaire in 2003 at age 33.
In 2015, Lens Technology went public, making her a billionaire and the world's richest self-made woman at age 45.
Today's estimated net worth: $5.9 billion
Jeff Bezos: 33
Amazon's founder and CEO became a self-made millionaire in 1997 at age 33 when Amazon's IPO raised $54 million. A quick two years later he achieved billionaire status at age 35.
Today's estimated net worth: $43.5 billion
George Lucas: 34
The creator of "Star Wars" and founder of production company Lucasfilm became a self-made millionaire in 1978 at age 34. His stake in Lucasfilm helped him make the jump from millionaire to billionaire at age 52.
Today's estimated net worth: $4.5 billion
Denise Coates: 38
The co-CEO of online-gambling firm Bet365 became a millionaire in 2005 at age 38 after selling her company for $40 million. Her 50% stake in Bet365 made her a self-made billionaire by age 47.
Today's estimated net worth: $3.8 billion
Meg Whitman: 40
The former eBay CEO, and current Hewlett-Packard CEO, became a self-made millionaire in 1996 at age 40. Two years later, at age 42, her net worth exceeded $1 billion after she took eBay public.
Today's estimated net worth: $1.89 billion