Before launching the computer software company that made him a millionaire, renowned investor Mark Cuban thought a different business idea would be his runaway hit.

At age 24, prior to creating his software startup MicroSolutions, Cuban decided to sell powdered milk as a recent college graduate eager to strike out on his own. He had very little cash on hand, the now 66-year-old tells CNBC Make It: “Less than $20.”

His stint as a powdered milk salesman lasted just about 30 days before he threw in the towel. Luckily for him, he didn’t have much money invested in the venture — “just enough to buy samples and realize no one wanted to buy them,” he says.

During that month, Cuban pitched his product to anyone who’d listen, he told serial entrepreneur Emma Grede on a July 15 episode of her “Aspire” podcast. “I remember taking samples to people, mixing it up like, ‘Look, milk’s expensive. We’re broke, right? This will save you money,” he said. “And just seeing the look on their face … Point taken.”

Cuban considered his product cost-effective, but “it did not sell,” he added.

Shortly after that, he launched MicroSolutions and, at age 32, sold that business to CompuServe for $6 million in 1990. Less than 10 years later, his second venture, audio streaming service Broadcast.com, sold to Yahoo for $6 billion. His estimated net worth is now $6 billion, according to Forbes.

Powdered milk may not have been lucrative, but the foray taught him a valuable lesson about failure, he told Grede: “[It] doesn’t matter how many times you fail. You only have to be right one time. Just one time.’