The euro's cash usage was caught in a vicious cycle: merchants stopped accepting physical currency because customers weren't using it, while customers abandoned cash precisely because fewer places took it. A self-reinforcing downward spiral that seemed unstoppable. But here's the twist—policymakers are now worried that the digital alternative has become almost too successful, potentially outpacing the systems designed to handle it. The shift from tangible money to electronic transactions is happening faster than anyone predicted, raising new questions about monetary control and financial infrastructure in an increasingly cashless society.