Joe, I'd buy a garage full of these buggy contraptions too.

There’s a documentary due out this fall that attempts to solve the ancient riddle of rich athletes, and why they quickly become poor athletes. It’s called Broke, and it’ll be released as part of the ESPN 30 for 30 series, volume II.

We’ve mentioned the film previously in reference to young, budding NFL stars who are already making unwise decisions with their recently-obtained riches. Specifically DeSean Jackson, the Eagles receiver who started Jaccpot Records with a bunch of homeboys from Cali, a business venture that could be successful, but history tells us that when athletes partner with old friends, the opposite of success is the most likely outcome. Even before he signed his five-year contract extension worth $47 million earlier this month, Jackson was already freely tossing around bills for Jaccpot, dropping $25,000 on a party last summer.

The ESPN documentary by Billy Corben interviews a variety of athletes from different sports, with Andre Risen–the five-time Pro Bowl receiver who declared bankruptcy in 2007–used to highlight the fight between NFL players and their bank accounts. The film’s synopsis refers to a 2009 Sports Illustrated study which revealed that 78 percent of NFL players are broke within three years of their retirement, and the usual factors of leaching friends, and a thirst for the glory and popularity that comes with being an obscenely rich dude are cited as the root causes.

Those symptoms for the broke athlete are undoubtedly true in many cases. But there’s perhaps a far more common, and far more simple motivation for spending that we overlook too often, and I was reminded of it after hearing these comments from Jets running back Joe McKnight in a recent interview.

If you didn’t make the same connection, here’s the important part in word form:

“I was into sports all the time. Year round, I played sports when I was five, all the way up to now. I never stopped playing. When I was young I used to play basketball, baseball, football, and track. It used to go year round, from summer league basketball to football. I could never get one of these [referring to the buggy]. Well, my mom never wanted to buy me one because she said I’m playing sports all the time.”

The intention here definitely isn’t to paint McKnight as some kind of free spender who’s destined to live off of government checks later in life. He seems like a pleasant, well-meaning, and budget-conscious young whipper snapper who just wants to buy several dune buggy contraptions, maybe mount a gun on one, and live quietly and peacefully. McKnight is currently slated to earn $490,000 in 2012, and as Shonn Greene’s primary backup this year he could significantly boost his stock, and start to position himself for a nice raise two years from now when he becomes a free agent.

But whether he meant to or not, McKnight highlighted another incentive for NFL players to spend, just a few weeks after Jamal Lewis hit a speed bump as he goes through the bankruptcy process. Young players can sometimes have few pleasures in life growing up as they play youth sports and then college football, so they want new and wild experiences when their hours of practice finally start to show up in their bank statements.

So they buy them. All of them.

Often we associate a lack of fun and the possession of very few nice, cool toys as a child with a low-income upbringing. And sometimes that’s true for NFL players. You saw The Blindside, right?

However, with McKnight and likely others, buying awesome things like eight buggies is about making up for lost time. They lost their youth to football, so now they become adult kids. Many remain reasonable about it, and stop after they’ve purchased a yacht or two, and a few nice vacations. But the temptation to allow that spending to grow still lingers.

Thanks for the video, Gang Green Nation