But it's not cash you control. You control the credit the bank issues to you when you make a deposit. And you rely on the bank not freezing that credit, and fai

But it's not cash you control. You control the credit the bank issues to you when you make a deposit. And you rely on the bank not freezing that credit, and faithfully redeeming it for cash when you make a withdrawal. The entire reason cryptocurrency was invented was to get around having to rely on trusted third parties to transact.