Adrian Peterson is a football legend. The running back was a runner-up for the Heisman Trophy and followed his college success by becoming the fastest running back to hit 10,000 yards in the NFL, among other achievements. But the surefire Hall of Fame ball carrier is carrying a rather slim wallet these days.

An ESPN report revealed that Peterson is broke, and owes more than $9 million to various creditors. While it’s unfortunately no surprise when athletes go bust, it is amazing how much money Peterson burned through on his way to the poor house. He’s earned nearly $100 million from his playing career. So what happened?

Adrian Peterson Was an All-Time Great at Spending Money

Unlike some of his peers, Adrian Peterson had a knack for spending money – whether it was his or not. He even managed to get in trouble for allegedly using money from his charity to help fund a sex party:

Peterson was also known for living it up.

His 30th birthday party will forever live in infamy. He reportedly flew more than 300 guests in first-class to the party, which featured a rented camel, world-class belly dancers, and this magnificent ice bar:

12 foot ice bar for @AdrianPeterson 30th birthday party. #30AllDay #IceOccasions pic.twitter.com/bR3lK1BdSP

— Tohn Hughes (@CoachTHughes) March 22, 2015

Adrian Peterson Wouldn’t Be Broke if He’d Just Invested in the Stock market

The thing is that Peterson could have lived his lavish lifestyle and still not ended up going broke. In fact, if he had saved a modest 10 percent of his income, his net worth would remain well into the eight figures today.

We ran the numbers on how wealthy Peterson would be if he had simply invested 10% of his cash earnings each year into a basic S&P 500 index fund that tracks the stock market.

For example, in his first playing year, Peterson earned $6,990,000 in cash salary. So what would have happened if he saved 10% of that – and from his earnings in each subsequent year – and put it into an S&P 500 fund?

Peterson would have started investing at the end of 2007, just in time for the massive market crash amid the financial crisis. Still, he’d be up today. Way up.

At this point, he’d have more than $24 million saved up in the S&P 500 index fund. His net worth would have jumped from $18.8 million to more than $24 million this year alone thanks to the sizzling stock market rally. Even for a big spender like Adrian Peterson, that would have been a lot of money.

Instead, thanks to his less than frugal ways, he finds himself deep in debt during the twilight of his career.