Nobody pays an extra $400 on a $500 card because of some sob story. They paid $900 for that card, because they thought it was a $900 card.
Sounds like a story where a seller simply said they needed $900 out of a card (what they paid for it is irrelevant), all the reasons given after that were embellished (and also irrelevant), and now somebody is looking to now get their money back out of this "card", and is looking at the original seller as the easy way out.
To some people I imagine the phrase "give me my money back or I'll out you on Net54" comes easier to some then it does to others.
Sometimes you need to own up to your mistakes.
We've all bought things we're remorseful about throughout the years.