- If they're already in possession of the recovered funds, then there's no reason for them to ask for more when they can easily deduct their own fees from the recovered funds!
Here in my country similar scams happen, but not involving cryptocurrencies and not involving the comission requirement.
Instead, scammers tell the victim they are the manager of his bank's agency and that his banking account was hacked, therefore they need their debit/credit card and every personal details to revert the transactions made by hackers and retrieve the money.
So they send a motorcycle messager to the victim's address (in the name of the bank), and tell the person to give him the card inside an envelope, addressed to the local police officer.
Target victims are usually elders, and they really trust the bank is trying to help them, since the call comes from an official number, as we can check on Google.
I don't know if scammers use top tier technology or if the schemes happen with the participation of banks' employees, though.