Yes of course; in a world where you can make money from lending out money that's all perfectly reasonable. In a world where you can't, then the sales pitch must change. Or banks switch to more complex/risky financial instruments that may not be insured against loss.

Safety deposit boxes usually aren't insured (or if they are aren't insured for very much or against very much), so if it came to that I would recommend researching that before doing such a thing as storing your money in one.