At 25, she owned 5 rental properties, but says investing in real estate was her No. 1 money mistake: 'I was really naive'

When Naseema McElroy was 25, she owned five rental properties. It was how she thought she was going to build her wealth.

By taking advantage of subprime lending practices that allowed borrowers with weak credit histories to easily obtain high-interest mortgages in the early 2000s, McElroy figured she would borrow as much as she could to purchase multiple properties and it would all work out in the end, she tells CNBC Make It.

Then about a year later, in 2008, the housing market crashed.

“I was really naive,” McElroy says. Suddenly, she owed lenders more than what her properties were worth. To avoid foreclosure, she says she was forced to sell two of the investments for less than what was left on their mortgages. Two other properties were foreclosed on, and eventually she says she had to declare bankruptcy.

Since then, the now 44-year-old labor and delivery nurse has grown her net worth to over $1 million, according to documents reviewed by CNBC Make It. She owns her primary home, but the majority of her wealth comes from investing in the stock market through broad-based index funds, documents show.