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George Foreman's big pay day came in 1999, when he bagged $138 million for selling naming rights to grill manufacturer Salton Image Credit: Gulf News Archive

For some, diplomas are (barely) worth the paper they're printed on. These star entrepreneurs jumped right in.

Many did it out of necessity; others had a mentor (or at least a backer looking to piggyback on their success). All, however, had a drive to build something of their own. Even at a young age, that commitment and passion can win over investors.

"Investors really look at the person and the quality of his or her idea more than their experience,” says Brad Burke, managing director of Rice University's Rice Alliance for Technology and Entrepreneurship, which incubates new companies.

10 tips on raising a young mogul

For all the new entrepreneurship programs popping up at business schools, there will always be a slew of born entrepreneurs who prove that high school diplomas, let alone fancy graduate degrees, might well be (barely) worth the paper they're printed on.

Here are just a handful of examples.

Jay-Z (Shawn Carter)

This high-school dropout grew up in one of Brooklyn’s roughest housing projects, dealing drugs before finding salvation in hip hop. In 1995 Carter took his first single to Def Jam Records, the company he ended up running from 2004 until 2007.

In 2008 he signed a 10-year, $150 million deal with Live Nation that gave him control over his records, tours and endorsement deals with companies like Dell and Budweiser.

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Self-made stars

George Foreman

This ubiquitous pitchman grew up poor in Marshall, Texas. Found a mentor, through Lyndon Johnson's Job Corps program, who encouraged the 15-year-old thug to box. Foreman would eventually win a gold medal at the 1968 Olympics.

His big pay day came in 1999, when he bagged $138 million for selling naming rights to grill manufacturer Salton.

He has since pitched brands like Doritos, KFC and Meineke, and has launched a line of environmentally safe cleaning products, a line of personal care products, a health shake, a prescription shoe for diabetics and a restaurant franchise.

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Simon Cowell

Caustic judge earned $75 million last year, thanks to his involvement with American Idol, Britain's Got Talent, musical talent show The X Factor and SyCo records, his production company.

The 50-year-old impresario dropped out of school at age 16 and landed a job in the mailroom at EMI. At 23 he left to start his own record label, Fanfare. Post-Idol, Cowell will shift his focus to a US version of the The X Factor, where he'll serve both as a judge and executive producer.

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Gisele Bundchen

When Bundchen was 14 years old a modeling scout discovered her in a Brazilian shopping mall. In 1996 she debuted at Fashion Week in New York City. She earned $25 million last year, thanks to contracts with Versace, Dior and other companies. She also has a line of sandals called Ipanema by Gisele.