Yah. They get that far without learning life skills, and they certainly don't learn any during their careers.
I have a feeling that they can't all be that dumb, and that there are forces in play that we aren't aware of.
I'd be curious to know a rule of thumb as to what fraction of salaries we see published actually wind up in the player's bank account. Taxes, agent fees, fees to set up trusts, a somewhat externally forced higher standard of living, etc etc, lead me to think that maybe they see 50% of the first million, and perhaps even a lower fraction of larger amounts.
That still seems like a lot of money - and for the truly elite player it is - but if you're an average player and you plan to live off the interest for the rest of your life after your playing career, you need to net out with more than just a couple million in this age of low interest rates. The $15M mentioned in the linked article is a little laughably high as a threshold, unless you expect to live as a jet-setter, but for a comfortable life it's somewhere in the middle.
Therefore players are sometimes magnets for every get-rich scheme out there that proposes to triple your money with zero risk. Even if you're careful, it can be easy to fall prey.