Probably a boring answer but I know my grandmother’s credit card information. I live with and help take care of her, so she doesn’t mind sharing it with me. Not like I’m planning to do anything nefarious, but I guess technically it could ruin her financially.
Man, for me it would be funny to do the opposite question.
“What secret do you know that could fix someone else’s life?”
I would tell half my family that they are a bunch of conservative hypocrites and that they waste so much f*king money showing others they have money. (Expensive cars, clothing and stuff).
Maybe if they stopped wasting money and being so critical of others, they would have actual friends and lasting relationships.
Sorry, i needed to vent.
FWIW I see you. :( Good luck with them.