Becoming part of the euro zone was a big commitment for Greece. It meant abandoning its control of the printing press, which can be a perpetual means of financing government deficits (spending in excess of taxation). But, after making that commitment, the Greek government ran its fiscal affairs in a profligate manner, not just during the recent crisis, but continually, even during the boom years of 2004–2006.
Given the absence of a printing press to finance its deficits, Greece's profligacy now requires deep fiscal reforms to allow it to repay its debts and also to remain in the euro zone. Unfortunately, there is substantial reason to doubt Greece's ability to meet that challenge. It is unlikely that Greece will be forced to leave the euro zone this year, owing to the likely support of other euro zone countries, which its recent fiscal reforms likely have secured. But within a few years, unless Greece undertakes substantial and additional reforms, it is likely that Greece will leave the euro zone.