At age 10, Diane Hendricks decided she wanted to work in the business world. It took years to achieve that goal, and decades for her career to build a fortune.

This week, Hendricks topped Forbes' recent American's Richest Self-Made Women list for the seventh consecutive year. Her estimated $20.9 billion net worth comes largely from her roofing materials company ABC Supply, which she co-founded with her late husband Ken Hendricks in 1982.

Hendricks, now 77, and Ken started the company after realizing there were precious few one-stop shops for roofing materials made by different manufacturers, she told Forbes in 2022. Roofers often bought directly from individual manufacturers, locking them into an ecosystem and allowing manufacturers to drive up prices.

They took out a $900,000 loan from Beloit Savings Bank and pledged everything they owned to launch their company and fill that gap, Hendricks said.

Within five years, ABC Supply had 50 stores, and it brought in $1 billion in annual sales for the first time in 1998, according to the company's website.

The secret to their success, Hendricks said, was filling a gap in the market — and raising the standard of respect and professionalism in contracting.

"We felt like we [roofers] weren't being treated with respect," said Hendricks. "That was part of our goal ... to build a company that would [help] the guy in the pickup truck, and provide service and respect to [everyone]."

'It's not a company that's ever going to be for sale'

Even before the Beloit, Wisconsin-based company grew to 900-plus locations, starting the company felt like a dream, Hendricks said.

Growing up on a farm in Osseo, Wisconsin, Hendricks dreamed of moving to a big city — Minneapolis, specifically — where she could wear blue suits and drive fancy cars, she said.

Then, after getting pregnant at age 17, she finished her senior year of high school from home. Instead of going to college, she worked a variety of jobs — even waitressing as a Playboy Bunny for a year — while trying to build a career in real estate.

"That's when I really started to look at a career, a career I'd always dreamt of having, which was being in business," said Hendricks.

Hendricks owns 100% of her company and has been its chair since 2007, according to ABC Supply's website. She still enjoys going to work, and plans to pass the company down to her children, she told Forbes in 2022.

"It's not a company that's ever going to be for sale," said Hendricks.

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