Text minor issues:
Gain from an opponent hand is strange, what happens if you Trader the gain, the opponent mantains their card? It is trashed (nothing indicates it should)? It goes to the supply?
I would make the treasure option trash or return to the supply the treasure first and then you gain it (see Thief's way of dealing with getting other people's things).
Also, it would be nicer to read for people used to regular cards if you use the standarized language ("When you do" -> "If you do", use "Choose one:" to indicate each choice, say "each other player", etc).
The card seems overpowered. +$3 for $5 already seems like something that would see a fair amount of action, and the Attack can be really devastating against Big Money type decks (Pillage is much weaker, for instance, and wrecks hands pretty badly). It is also swingy that you need to decide weither to cash in the card, and sometimes discover you steal a couple of nice Treasures and other times you get nothing in return. Deciding weither to trash Mining Village is already difficult some times.