It's not surprising that few money managers have enough talent to make 20% per year for very long. Someone who can make that sort of return quickly ends up with more money than they can easily invest. For them, signing up to invest other people's money is stupid because it means that the opportunities they find will result in profits owned by other people. Far better to trade on their own account.
In short, the people you find working as money managers are naturally going to be the B+ students and below.
