Well, you actually can!
You can withdraw your BTC to a cold storage and lock it up in a bank safety deposit box.
LoL - this is the coolest answer of the whole thread!
However, I guess this was not what the guy was thing at. Since the person seems not to know exactly how Bitcoin works, he should perhaps open an account on Coinbase which is very simple to understand and it it allows the customers to sell the Bitcoins and send the FIAT money to the bank account.