Tho they caused much of their problem themselves, two things have and are making it worse. Greece invested in American bank derivatives, we know what that helped cause here. American banks are still shorting / betting against the Euro and Greece making the issues that much worse.
Wall Street and the banksters (banking gangsters) caused much more of an issue then just here at home.
Bankster : Let us get sub prime mortgages, repackage them and sell as AAA investments, then bet against them.
*Go do some research and see how many countries, States in the USA, retirement pension funds and more were all sold this junk. Instead of going after too big to fail, countries, states , counties are going after the middle class for more instead of the banks who did the robbery and already got our money to be bailed out.
Short selling in general can cause huge issues.