As someone not wholly familiar with government bonds, let me ask- does this mean that private creditors, aka individuals like you or I, are taking a 50% loss on investments? Or is this at a corporate or governmental level?
Both. Pension funds and the like often invest in government bonds; traditionally they're a safe investment used to hedge against riskier ones like stocks. With the latter you know there's no guarantee of performance, but you expect a risk premium in the firm of a dividend or accelerated growth. 'Bond' is another word for 'promise' so you should be able to rely on it. Saying that 'people knew the risks' of investing i…
"Risk-free" is a theoretical concept. Roughly speaking, it's an assumption used to simplify financial equations, analogous to assuming "no friction" in high-school physics problems when the friction coefficient is small enough.
The usual rationale for assuming that a country will always pay back its debts is that it can print its own currency at will. But this is not the case for the euro, since an individual member country cannot freely print euros. It's also not the case for dollar-denominated bonds issued by emerging countries. Indeed, even bonds issued by the two largest and more stable powers in the world (US and Japan) aren't 100% risk-free. They might be able to keep borrowing money and not defaulting, but likely at the cost of inflating their currencies, i.e, investors still get the nominal dollars and yen back, but they will be worth less in terms of goods. The closest thing to risk-free is an US Treasure bill.