What were you doing during your 20s?
Probably attending a college or university, enjoying your youth, and having new experiences away from home.
Many of technology's most notable billionaires were doing no such thing.
Michael Dell for instance was already investing in stocks and precious metals before he graduated high school.
During their early years, Dell and the other seven entrepreneurs were busy laying the foundations for some of today's biggest and most recognizable companies.
Mark Zuckerberg was a billionaire by 23.
Zuckerberg, a Harvard drop out, was already a billionaire from Facebook at the age of 23.
By the time Zuck was 25, Facebook had an estimated 500 million users worldwide. Also during this time Zuckerberg was involved in various legal disputes initiated by others who claimed a share of the company because they helped to set it up.
When Zuckerberg was 26, he was honored as TIME Magazine's person of the year.
Bill Gates started his own company, developing a programming language for a new computer system.
In his early 20s Bill Gates dropped out of Harvard and decided to start his own software company with friend and co-founder of Microsoft, Paul Allen.
Microsoft's official history says that in 1975, when Gates was just 20 years old he and friend Paul Allen were inspired by the MITS Altair 8800 a computer system. Gates and Allen began to develop a BASIC language for the Altair.
One month later, Gates and Allen sell BASIC, the first computer language program for a personal computer, to Microsoft's first customer, MITS of Albuquerque, NM.
Steve Jobs trekked to India during his 20s and had a life-altering experience, shortly after he returned from his trip he became a Buddhist.
At the age of 19, Steve Jobs took a job as a technician at legendary game company Atari.
By the time he was 20 he had a reputation for "being the smartest guy in the room" and but also difficult to work with.
At the age of 21, Jobs and long-time friend Steve Wozniak formed their own company, selling circuit boards. They named it "Apple Computer Company" after a happy summer Jobs had spent picking apples.
See the rest of the story at Business Insider