This game isn't PVP. Those people spent 100 hours getting other stuff they are now trading for the stuff they want. Its not like they are getting it from the air.
As for plat, it didnt devalue with this exploit. plat isnt coming in or out with this, so it has no effect
EDIT: The pvp comment was just to point out that just because that people now have items, that doesn't make you any better or worse. nothing has changed