I have been almost successfully scammed and there is one thing that stood out of all this text that I can relate: the author was mentally tired.

I wasn't tired, but I got a call at 8AM on a Saturday as I was just about to wake up, and I hadn't slept very well. You may be very aware of all the latest security practices, but in the end you are human, a big bag of emotions swirling around. And it only takes a moment where you are vulnerable to scam you successfully.

The lesson here, I think, is: it could happen to you.