I think their hope is that it keeps the larger population from being afraid their money is exposed to government intrusion so they pull their money out. And in a time of low or zero interest rates, your mattress may be safer than a bank. At least it’s safer from the government. That is, it’s a lot harder for them to get at it. :)
Robberies would increase if folks kept their money at home. That’s the one thing I’d be worried about. That and a house fire.