Socialism is an unsustainable economic system, it cannot exist without a large and vibrant private sector on which to suck the bloody funds from. When you have countries in which the blood suckers, the public sector and welfare recipients become too large and the private sector too small and weak, then your economic system will fail.
President and Obama has declared war on capitalism and the middle class and the unlimited immigration into this country are combining to drive this country into bankruptcy. Greece is a small enough country that a "bailout" from Europe might prop it up for a few years, at the risk of bringing down European countries along with it.
The United States on the other hand is too big to bail.