Hi Phat, I am not economic major or business grad but from what I have seen in the media and on various documentaries on the subject Greece has been allowing the corporate banks to cook their books and they bought into the credit default swaps too. Now that the chickens are coming home to roost they are the ones left holding the bag.
Very complex problem that has been compounded by from what it seems like, greed and stupidity. Drachmas here we come.
"You were not there for the beginning. You will not be there for the end. Your knowledge of what is going on can only be superficial and relative" William S. Burroughs