as a visitor you can withdraw up to 600 euros from an atm in greece with your foreign bank card.
this opens up an opportunity for tiong syndicates to go to greece and charge a premium to locals for "helping" them to withdraw euro's out of atm's.
No, it does not work this way. The tiongs must have their deposit in the bank before they can make any withdrawal. At this time of financial chaos in Greece, which tiong would want to leave his money in any Greek bank? Tiong already vanished long time ago.
It might take a Warren Buffet to pump in millions into a Greek bank and wait for IMF to save Greece and when they have turned around, the returns would be a windfall. No risk, no gain but it is a calculated risk.