Also, Greece was always going to fail, and that had nothing to do with its political ideology.
Simply, a country that produces nothing and has rampant corruption amongst its leadership will always fail, no matter the form in which the corruption appears (socialist state, bureaucratic state, etc).
Similarly, the issue facing a lot of European countries is that the age demographic is top heavy - a dwindling youth population is working to support a growing non-productive retiree population. No matter what system you have, if the majority of resources are consumed by non-productive members of society, you are going to have sustainability issues.
In US, a big issue is the skillset of workers. Because manufacturing is quickly being outsourced where cost of labor is order of magnitudes cheaper (even within the US, to immigrant workers willing to work for far less), there is greater pressure to shift the skillset of the newly displaced American worker. The problem is that our education system is shite at teaching math and sciences (the most useful skillsets nowadays), and even though we have the best Universities in the world, the high-technology fields (the area that the US is now specializing in) are dominated - especially at the PhD level, by immigrants who will frequently send money from their high paying jobs to relatives back in their home countries, or who - out of disdain for American culture - voluntarily exclude themselves from local "indigenous" communities. My parents and their pool of friends are a good example - I've seen this personally. Our "capitalist" system failed to produce an education system that could appropriately equip a basic majority of its citizenry with the skillset necessary to be competitive in the global environment. We have an overabundance of history/liberal arts majors to the extent that we have to import engineers, mathematicians, and computer scientists. And we've had that problem for the past century.
Lack of education is a key part of our employment crisis. I run a software development company and I get more solicitations for business partnerships or from hardware/software suppliers from Indians than I do for Americans (the ratio is a ridiculous 10:1).
But at least banks like Goldman Sachs use High Frequency Trading software capable of executing a volume of trades that can nuke the entire global capital market in the space of 15 minutes, and basically hold the entire world hostage. So...I guess we can take solace in that (?).