An entrepreneur who spent 5 years interviewing 21 self-made billionaires asked every single one how they made their first million dollars — here’s what they said

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• Self-made billionaires don’t get to the three-comma club without first becoming millionaires.
• Rafael Badziag interviewed 21 billionaires for his book, "The Billion Dollar Secret," and they all told him how they made their first $1 million.
• Many earned it through founding their own business or through investments.
• Visit Business Insider’s homepage for more stories.

Many of the world’s richest billionaires built their wealth from scratch.

Rafael Badziag, an entrepreneur and expert in the psychology of entrepreneurship, spent five years conducting face-to-face interviews with 21 self-made billionaire entrepreneurs around the world (defined as those with a net worth of at least $1 billion) and researching their lives and companies. 

In his book "The Billion Dollar Secret: 20 Principles of Billionaire Wealth and Success," he shared how each of those billionaires made their first $1 million. Some earned it through the businesses they founded, while others earned it through investments or by working for someone else’s company.

For the purposes of this slideshow, unless otherwise specified, we assumed that any of Badziag’s subjects whose net worth we were not able to verify with Forbes’ net worth listings is worth at least $1 billion. All information on the billionaires comes from Badziag’s book.

Mohed Altrad made his first million in the scaffolding business.

PASCAL GUYOT/Getty Images

Net worth: $2.6 billion

Altrad is the founder and chairman of Altrad Group, which offers services and equipment for the construction industry in more than 100 companies and is a world leader in scaffolding. Altrad owns the Montpellier Hérault Rugby Club and has written three novels.

Tony Tan Caktiong made his first million in the food service business.

NOEL CELIS/Getty Images

Net worth: $3.6 billion

Caktiong is the founder and chairman of Jollibee Foods, Asia’s largest food service company. It operates 13 restaurant chains and has more than 4,300 restaurant outlets in 18 countries worldwide.

Jack Cowin made his first million with fried chicken.

Mark Kolbe/Getty Images

Net worth: $1.6 billion

Cowin is the owner, chairman, and managing director of Competitive Foods Australia, one of the country’s largest food processors. It’s also the country’s largest franchisers of restaurants, introducing fast food to Australia with KFC, Burger King, and Domino’s Pizza.

See the rest of the story at Business Insider

See Also:

• The richest man in Hong Kong is funding an entire college class’ tuition for up to 5 years — here’s his incredible rags-to-riches life story
• Bernard Arnault just joined Jeff Bezos and Bill Gates in the 3-person club of people worth more than $100 billion each. Here’s how the French billionaire makes and spends his fortune
• This is how the world’s 5 youngest billionaires spend their time and money

SEE ALSO: An entrepreneur who interviewed 21 billionaires says the same 6 habits helped make all of them successful

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Source: Business Insider – hhoffower@businessinsider.com (Hillary Hoffower)