I also do not fully understand, why this is so. But before the Euro started our politicians drummed the big drums for it and repeated like machine guns, that such a situation could never, never ever (I swear!) happen ... But after Greece nearly went bankrupt in 2010, I guess, our chancellor said that this would be the "one and only alternative".

The problem is (as much I understood), that when one Euro country is going bankrupt, this will damage the confidence in the currency as such. But I don't fully understand the reasoning, as I said.

It also could be, that it was the "one and only alternative", because some big German banks would have been severely damaged back then (back then, they held a big amount of the Greek debts) ... Today, only the tax payers will be damaged, what is not so bad ...