It's only the banks which earn profits by lending our invested money as loans for interests.The only benefit which we could get is that our investment remains safe but not safe from deflation.
I don't know where you saw the deflation. All Fiat are experiencing inflationary pressures. Governments are constantly using emissions to pay for their mistakes in the economy with our money. I never keep my money in a Bank. This is not profitable from an economic point of view. Bitcoin is really the most effective tool for protecting our savings to date.