The smarter ones, ends up hiring a financial company to take care of their business. I agree that the older generation didn't made that much, but we hear stories about rich players who nobody heard about, because they made good investments.
An example is Vinnie Johnson, the Pistons guard, who never made a dime over 800k in his career per year, and yet he has a 500+ million dollar empire today. How? He created an auto parts company, that spreads across all over USA, and response very quickly to any failure. See how he was smart with his money? Even someone as famous as Magic Johnson, didn't made as much as Malik Beasley did in his career, and yet he owns 1+ billion networth now, thanks to his investments. You just need to realize, while earning, those checks will not keep on coming, so use those to buy something that will keep on getting you paid.