I'm not entirely sure how you imagine Visa's fees protect you from Linux kernel zero days. More than likely, the unwieldy infrastructure with massive technical debt accrued over decades has a much larger attack surface and uses a myriad of more or less obsolete technology.

Also, the payment system should not be confused with the banking system. Complete control over the payment system would give the attacker the ability to deny payments or make fraudulent ones, but would not, for example, allow the attacker access to accounts not linked to a payment instrument, or allow them to circumvent the limits set on such instruments.