"sitting on it" would require literally keeping it in cash in your safe. If put "in a bank", unless you mean a safety deposit box, is (to some approximation, in

"sitting on it" would require literally keeping it in cash in your safe. If put "in a bank", unless you mean a safety deposit box, is (to some approximation, in theory, in the not to distant past, maybe) reinvested by the bank. That is how the bank makes money.