When Raghib "Rocket" Ismail signed the richest contract in football history, he thought he was set for life. But as he told Sports Illustrated, Ismail's then-unheard-of $4.55 million salary disappeared almost as fast as he earned it. "I looked at my bank statement," he said, "and I just went, 'What the...?'"

It seems impossible for multimillionaire athletes to go broke. However, Sports Illustrated found that after two years of retirement, 78 percent of NFL players are bankrupt or under financial stress. How can that be possible?

There are many contributing factors to the suddenly wealthy becoming suddenly living hand-to-mouth again. Horrific spending habits, bad investments, generosity and child support can put the wealthiest athlete into the poor house.

Spending

The most outrageous story of an athlete going broke doesn't come from the NFL. The NBA's Antoine Walker earned over $100 million during his career, but was arrested in 2009 for writing bad checks. What happened to his nine-figure fortune?

He spent it all.

Boston.com's Shira Springer wrote:

Walker turned the pavement surrounding his home into a virtual luxury car lot. Two Bentleys, two Mercedes, a Range Rover, a Cadillac Escalade, a bright red Hummer. Often, the vehicles were tricked out with custom paint jobs, rims, and sound systems at considerable added expense.

Walker also loved expensive watches, like bejeweled Cartiers, and ordered "closets full" of custom-tailored suits.

Walker loved to gamble, in more ways than one. His constant trips to Vegas were a constant drain on his bank account. Fifty thousand doesn't sound like much compared to $110 million. But do the math: A $50,000 weekend of VIP living, every other weekend for 12 years, is $15.6 million—roughly 15 percent of Walker's net income.

Add in the Bentleys and the Cartiers and the mansions and the suits, and you can see why Walker is now living on cold cuts and cold cereal in the NBA D-league.

Bad Investments

Baltimore Colts legend Johnny Unitas was one of the greatest quarterbacks ever to play the game. Unfortunately, his ahead-of-his-game field-management skills didn't translate to the boardroom. He used his career earnings to buy ownership of "a chain of bowling establishments, a prime-rib restaurant, an air-freight company and Florida real estate investment."

Those ventures were unsuccessful to various degrees, but what finally defeated Johnny U was the volatile tech sector. Borrowing or accepting millions from the City of Baltimore, the State of Maryland and other companies, Unitas bought a circuit board manufacturer.

When the business failed, Unitas was forced to file bankruptcy—leaving a legal mess behind that dragged on for over a decade after his death, with Maryland taxpayers footing much of the bill.

Child Support

Former Denver Broncos tailback Travis Henry has famously fathered nine children by nine different women.

Henry's lawyer, Randy Kessler, told the New York Times that Henry's child support obligations total over $170,000 annually. For a former late second-round draft pick who was cut one year into his most lucrative contract, that's a very significant amount.

Henry's had other personal and professional problems—and his children's mothers' lawyers insist he's squandered much of the savings that should be going to them. But he's struggling to keep up with payments assessed back when he was earning NFL money.

It may be only a matter of time before Henry can't run from his obligations anymore.

Generosity

Former Detroit Lions defensive tackle Luther Elliss has a problem providing for his many children, too: the five biological children he's fathered with his wife, and the six children they've adopted, some of whom have special needs.

Elliss' lawyer, Darryl Chimko, told the Associated Press:

If you've ever met a man who does all the right stuff Christians say they do, it's Luther and his wife, if you walked up to his house and needed $5.00, he'd give it to you and then find a way to feed his family.

Unfortunately, that's exactly what Elliss has been left to do: find a way to feed his family.

Elliss was a fixture on the field for the Lions and a fixture in the Detroit community. He was frequently involved in charity events and invested heavily in local businesses. For his relatives, Elliss paid for things like landscaping and a wedding.

The Utah native also put down roots in the area, taking out a $1.6 million mortgage on a home in nearby Oakland Township. Unfortunately, the business investments didn't pan out, and the recent collapse of real estate values deflated the value of Elliss' home and other Detroit-area properties.

Ironically, Elliss is now the recipient of the charity he used to give out: Elliss moved his family back to Utah, and local friends and churches are paying his bills, according to the Deseret News.

Elliss might eventually get what most bankrupt athletes dream of: a second career in sports. He's working on a degree in sports management while volunteering as an assistant defensive line coach.

Lessons Learned

Elliss told the Deseret News:

It's not just professional athletes that are doing this. Look at our country—it's trillions in debt. Where are we going? We're still spending. It's something I've been advocating recently, especially at younger levels, we need to educate them in the basic finances and understanding you can't spend more than what you make.

While teams, the NFL and the NFLPA offer plenty of resources for players, many aren't thinking about how short most pro careers are. If most weren't convinced they were going to succeed, they likely wouldn't be in the pros to begin with.

Many Americans spend everything they earn, whether that's $25,000 a year or a $25 million signing bonus. But as dangerous as that is for regular Joes, it's even more so for the pros whose earning power is always one snap away from disappearing.

No matter how today's NFL players choose to spend their money, they need help saving enough to sustain themselves when those game checks stop coming.