What is the root cause?

Basically it is back to the age old human nature of 'fear and greed'. The chase for yield that bankers go for causes them to buy bonds such as Greece etc, just to get the extra 1 to 2% of yield, so that they can enrich themselves by having the bank pay them big bonuses. In the end the shareholders and the bank are left holding the bag, while the greedy 'fat cat' bankers become millionaires. What does Obama and ECB do about it? Nothing because those are their friends. Cronyism is truly alive...