How would one "accidentally" wire transfer millions of dollars? At $10k in America, KYC and AML laws force banks to step through extra layers of verification to wire such amount. It's virtually impossible for someone to accidentally wire millions, which would likely involve a mandatory in-person meeting with the bank customer to verify their credentials and purpose.

If somehow you get through an in-person meeting with a bank branch manager to unwittingly wire millions of dollars, and the topic of how much money you're wiring and the exact purpose of wiring such a high amount isn't brought up, and you somehow still accidentally wire millions of dollars away without anyone ever bringing up the amount and purpose of the transaction, then I'm sure you'll still be able to recover that money back because banks are required to actually validate transactions of that size with KYC, AML, etc. laws. Only cryptocurrencies allow one the ability transmit this amount of money in seconds.