I am curious how a millionaire would guarantee the safety of his money, given that the FDIC only insures up to $250K of an individual's deposits at a bank.

If someone had $3 million that they wanted to put into the bank, would they have to open up 12 different bank accounts and deposit $250K into each one, so that all of his money is insured by the FDIC? Or is there an easier way to guarantee the safety of all his money?