Pro athletes in the NFL, NBA, MLB and NHL earn millions fast, but most lose it just as fast — a warning about what sudden wealth does to people with no financial training.

• Most NFL players hit money trouble within two years of retiring, and most NBA players within five.
• Taxes take the biggest bite: a $100 million NFL contract nets closer to $40 million, and players owe filings in every state they play in.
• Agents, managers, family, hangers-on and celebrity-level spending habits all drain the rest.
• Lenders offer young college athletes cash up front against future contracts, then claim a big share of their pay, so many start their careers already in debt.
• Careers are short — the average NFL career lasts about three years — and one injury can end the money for good.

Outlook: Nothing about this is likely to change soon, since leagues keep handing huge sums to teenagers, though new rules letting college athletes earn from their own name may give some a head start on managing it.