Mark Zuckerberg had $1 million in the bank at the ripe age of 22, while Larry Ellison didn't reach millionaire status until age 42. Today, they're both billionaires.
Some successful entrepreneurs strike it rich early on. For others, it takes decades.
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
Larry Ellison: 42
The founder and CEO of Oracle became a self-made millionaire in 1986 at age 42. Shortly after, he achieved billionaire status at age 49, thanks to his stake in Oracle and the company's rapid growth.
Today's estimated net worth: $43.6 billion