A lot of pro athletes come from disadvantaged backgrounds where they haven't really become used to managing money beyond a hand-to-mouth way of living and then all the sudden they have tons of money in their laps that seems limitless. So basically a lot of them end up burning through it all and being essentially broke after their careers end.

A former NHL player wrote about this issue (getting handed a bunch of money at a young age). [1]

1. http://www.theplayerstribune.com/the-new-avery-rule/

I see where you are coming from but I think it's worth mentioning that a disproportionate amount of people born in the upper classes have also never had to manage their own money.

They have at least probably observed their parents managing money with a more long-term view.

Expertise in their core domain does not transfer to other domains and you can be as good with your body as any because of discipline and hard work it doesn't say much about how good you are going to be when the work does not involve your body.

Doesn't work always involve your body? Your brain is a muscle and part of your body, right? Not to mention be healthy plays a huge role in your productivity. Learning how to be discipline and focus is something all professionals of all levels work to get to and maintain. So, if they're able to transition that energy and concentration once out of the sport, it's to no surprise they'll be successful.

i can't speak to their respective backgrounds, but there was an ESPN documentary not too long ago that explored the post-playing career trajectories of professional athletes for major sports

Edit: ^^yeah, "Broke" that's the one

I didn't think Magic Johnson was going to make it past the 90's.

Nope.

http://www.npr.org/2015/01/27/381724445/how-do-some-highly-p...

See also the ESPN Documentary (a good one) called "Broke."