Most of it probably either got funnelled offshore by organized crime or is simply spent and gone. They could still go after people to try to recover it, but lots of it is probably blood from a stone at this point.Find the $15 Billion in payments of CERB etc during the COVID times. Recover the money FFS.
Though by all means, if they can find recoverable assets to recoup fraud, go for it. There’s probably a lot more money to be made going after illegal offshore tax dodges and forfeitures for major money laundering, given how rampant that is.