Given your previous comments with regard to your knowledge of finance you know this isn't such an easy thing. Their financial system is intimately tied into the euro and remaining part of the EU.
If the Greeks produce X euros worth of goods/serviecs and consume Y euros for Y < X, this should be a minor problem at best - paperwork, really. The actual problem is that Greece can't pay for their current levels of consumption. They haven't been able to pay for consumption in quite a while actually, but previously EU lending propped them up.
This is why Argentina's default wasn't anywhere near as bad - they were fairly close to consuming as much as they produced.
Unlike Greece, Argentina also instituted necessary reforms - for example, import substitution and breaking sticky wages via a 13% nominal wage cut for govt workers and pensioners [1]. Greece has steadfastly refused to do these things in spite of having ample time.
[1] Recall why Keynesians promote inflation - to inflate away real wages, which this cut also did.
This is why Argentina's default wasn't anywhere near as bad - they were fairly close to consuming as much as they produced.
Unlike Greece, Argentina also instituted necessary reforms - for example, import substitution and breaking sticky wages via a 13% nominal wage cut for govt workers and pensioners [1]. Greece has steadfastly refused to do these things in spite of having ample time.
[1] Recall why Keynesians promote inflation - to inflate away real wages, which this cut also did.