It's a long serie of mistakes that led us there. Maybe european leader should have stop postponing the crash and let greece default on all its debt to private creditor and let the impacted banks to go bankrupt like Credit Agricole for instance. But because in every major banks in europe, commercial banking and investment banking are not seperate activities, along with the banks bankruptcy a lot of people would have lost a lot of money.

So French and German politicians did not want this to happen. Greece was not alone to have financial problems, Ireland, Spain and Portugal had some as well but after a long austerity cure they are now stable. But austerity just didn't work as expected in Greece.