Nothing on the scale of the OP, but I had a pretty convincing scam attack about a year ago. (I may have posted this before). So, I received an email from a well known co-worker/friend, who also retired about 10 years ago. It said he had a friend with a seriously ill daughter that lived here in the states, and that he wanted to send her $$$ in gift cards. The problem was, he said, he couldn't get the gift cards that she wanted in his country.
He asked me to get the cards and send them to him and he would reimburse me for them immediately. I told him "okay" where do I send them? Then he came back and said, well to speed things up, I could just scratch off the secret codes on the back of the cards and send those to him.
(major warning #1). Additionally, he thanked me in the email using language that was "uncharacteristic" for him.
(major warning #2) So, I asked him a question that only someone that worked with us would know the answer too.
Never heard back.
Apparently his primary email account had been hacked and the scammer was sending such emails to folks on his contact list. Later on, I called him to let him know what had happened.