Jan Koum, the CEO and cofounder of WhatsApp, once lived on food stamps before Facebook made him a billionaire.
Net worth: $7.7 billion (according to Forbes)
Koum, 37, came to the US from Ukraine when he was 16 years old. His family, struggling to make ends meet, lived on food stamps that they picked up a couple blocks away from Koum's future WhatsApp offices in Mountain View, California.
In 2009, he and cofounder Brian Acton launched the real-time messaging app with an aim to connect people around the world. It essentially replaces text messaging.
WhatsApp, which now has over 600 million global users, agreed to a $19 billion buyout from Facebook earlier this year.
The deal made Koum a multibillionaire.
Jack Ma taught English before founding Alibaba in 1999.
Net worth: $20.2 billion
Born in Hangzhou, China, Ma grew up in poverty. He couldn't get a job at the local KFC. He failed the national college entrance exams — twice — before finally graduating and starting his career as an English teacher.
Then, in 1995, he had his first visit to the US. He saw the internet for the first time.
Recognizing that there was little in the way of Chinese content online, he started China Pages, a directory that was arguably the very first Chinese web startup. It promptly failed.
In 1999, he founded Alibaba. Today, the online retailer handles double the merchandise of Amazon. With September's IPO, Ma became China's richest person.
Elizabeth Holmes started her blood diagnostics company when she was 19. Now at 30, she's a billionaire.
Net worth: $4.5 billion
When Holmes was a 19-year-old sophomore at Stanford University back in 2003, she started Theranos, a blood diagnostics company that makes blood testing cheap.
The Palo Alto startup has 500 employees, a reported $400 million in funding, and a $9 billion evaluation.
Holmes has always been precocious — she taught herself Mandarin in her spare time when she was growing up in Houston. She was filing patents before getting to Stanford. And now she's worth billions.
Ingvar Kamprad was raised on a farm in Sweden before founding IKEA.
Net worth: $3.9 billion
When Kamprad was a 7-year-old boy growing up in rural 1920s Sweden, he sold matches to his neighbors.
He soon moved up to pencils, greeting cards, and Christmas ornaments. At 17, he founded a company called IKEA, short for Ingvar Kamprad from Elmtaryd, Agunnaryd, named for his hometown. At 21, he started selling furniture — and the IKEA empire had begun.
Today, the manufacturer has over 340 stores in 42 countries, $36 billion in annual sales, and the New Yorker has called the company the "invisible designer of domestic life."
Yet Kamprad remains frugal — the 88 year old refuses to fly anything other than economy class.
Starbucks' Howard Schultz grew up in a housing complex for the poor.
Net worth: $2.1 billion
In an interview with British tabloid Mirror, Schultz says: "Growing up I always felt like I was living on the other side of the tracks. I knew the people on the other side had more resources, more money, happier families. And for some reason, I don’t know why or how, I wanted to climb over that fence and achieve something beyond what people were saying was possible. I may have a suit and tie on now but I know where I’m from and I know what it’s like."
Schultz ended up winning a football scholarship to the University of Northern Michigan and went to work for Xerox after graduation. Shortly after, he took over a coffee shop called Starbucks, which at the time had only 60 shops. Schultz became the company's CEO in 1987 and grew the coffee chain to more than 16,000 outlets worldwide.
Born into poverty, Oprah Winfrey became the first African American TV correspondent in Nashville.
Net worth: $3 billion
Winfrey was born into a poor family in Mississippi, but this didn't stop her from winning a scholarship to Tennessee State University and becoming the first African American TV correspondent in the state at the age of 19.
In 1983, Winfrey moved to Chicago to work for an AM talk show, which would later be called "The Oprah Winfrey Show."
At one time, businessman Shahid Khan washed dishes for $1.20 an hour.
Net worth: $4.4 billion
He's now one of the richest people in the world, but when Khan came to the US from Pakistan, he worked as a dishwasher while attending the University of Illinois. Khan now owns Flex-N-Gate, one of the largest private companies in the US; the NFL's Jacksonville Jaguars; and Premier League soccer club Fulham.
John Paul DeJoria, the man behind a hair-care empire and Patron Tequila, once lived in a foster home and his car.
Net worth: $3.2 billion
Before the age of 10, DeJoria, a first generation American, sold Christmas cards and newspapers to help support his family. He was eventually sent to live in a foster home and even spent some time in a gang before joining the military.
With a $700 dollar loan, DeJoria created John Paul Mitchell Systems and sold the shampoo door-to-door while living in his car. He later started Patron Tequila, and now invests in other industries.
Forever 21 cofounder Do Won Chang worked as a janitor, gas station attendant, and in a coffee shop when he first moved to America.
Net worth: $5.2 billion
The husband-and-wife team — Do Won Chang and Jin Sook — behind Forever 21 didn't always have it so easy. After moving to America from Korea in 1981, Do Won had to work three jobs at the same time to make ends meet. They opened their first clothing store in 1984.
Forever 21 is now an international, 480-store empire that rakes in around $3 billion in sales a year.
Ralph Lauren was once a clerk at Brooks Brothers dreaming of men's ties.
Net worth: $7.8 billion
Lauren graduated high school in the Bronx, N.Y., but later dropped out of college to join the Army. It was while working as a clerk at Brooks Brothers that Lauren questioned whether men were ready for wider and brighter designs in ties. The year he decided to make his dream a reality, 1967, Lauren sold $500,000 worth of ties. He started Polo the next year.
Leonardo Del Vecchio grew up in an orphanage and later worked in a factory where he lost part of his finger.
Net worth: $18.4 billion
Del Vecchio, who founded Luxottica in 1961, was one of five children who was eventually sent to an orphanage because his widow mother couldn't care for him. He would later work in a factory making molds of auto parts and eyeglass frames.
At the age of 23, Del Vecchio opened his own molding shop, which expanded to become the world's largest maker of sunglasses and prescription eyewear with brands like Ray-Ban and Oakley.
Legendary trader George Soros survived the Nazi occupation of Hungary and arrived in London as an impoverished college student.
Net worth: $24 billion
In his early teens, Soros posed as the godson of an employee of the Hungarian Ministry of Agriculture in order to stay safe from the Nazi occupation of Hungary. In 1947, Soros escaped the country to live with his relatives in London. He put himself through the London School of Economics working as a waiter and railway porter.
After graduating, Soros worked at a souvenir shop before getting a job as a banker in New York City. In 1992, his famous bet against the British pound made him a billion dollars.
Oracle's Larry Ellison dropped out of college after his adoptive mother died and held odd jobs for eight years.
Net worth: $48 billion
Born in Brooklyn, N.Y., to a single mother, Ellison was raised by his aunt and uncle in Chicago. After his aunt died, Ellison dropped out of college and moved to California to work odd jobs for the next eight years. He founded software development company Oracle in 1977, which is now one of the largest technology companies in the world.
Now he's stepped away from his CEO responsibility — but continues to lead a fabulous life.
Roman Abramovich was orphaned as a child. Now the Russian tycoon owns the Chelsea football club.
Net worth: $9.5 billion
Abramovich was born in 1966 in Saratov, Russia. His mother died when he was 18 months old. His father died when he was four.
Orphaned, he was taken in by his uncle in Moscow and his grandparents in the northern province of Komi.
He went to Russia's Industrial Institute for college and then started trading oil products in western Siberia.
The Guardian reports that his "big break" came in 1992 when he caught the favor of Boris Berezovsky, one of Russia's premier tycoons as the country moved into capitalism.
Berezovsky fled to the UK after fraud charges. Abramovich took the reins of his empire, accumulating "80% of Sibneft, Russia's fifth-largest oil company; 50% of Rusal, the Russian aluminium oil monopoly; and 26% of Aeroflot, Russia's national airline," the Guardian reports. Then he got into private investments.
Today, Abramovich is one of Russia's richest people, and he has toys like the world's largest yacht, a Boeing 767, and the Chelsea Football Club.
Bonus: his daughter has an Instagram that shows what it's like to be an heiress.
