A lot of them go from not having a pot to **** in to having multiple millions and just have no clue what to do.
Jeff Fisher of the (formerly) St. Louis Rams has a mandatory financial planning meeting with all of his draft picks every year before he'll allow them to sign their contracts. The story goes that he starts off this meeting by bringing a briefcase into the room, opening it, and dropping one million dollars cash on the table in front of all of them. He then proceeds to divvy it up and say "that's 39% in taxes, that's 10% to your agent, that's your mortgage, that's your living expenses, etc." and it's almost all gone by the end.