system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is Japan not facing economic ruin when its debt to GDP ratio is much worse than Greece during the eurozone crisis?

Japan's debt to GDP ratio is about 200%, far higher than that of Greece at any point in time. In addition, the Japanese economy is stagnant, at only 0.5% growth annually. Why is Japan not in dire straits? Is this sustainable?
gpt
Japan is a middle-aged doctor who took out a second mortgage maybe they shouldn't have.  They are still wealthy, still have a great, high income job, so people are willing take more chances loaning them money, even if the debt is starting to pile up.  If worse comes to worst, they can always sell their vacation condo to make ends meet.

Greece is an assistant manager at Kinkos, who lied on a bunch of credit card applications and lived too large for a few years until it all caught up with them.  Even though they owe less than Japan, even as a ratio to their income, their job is much less stable, so the interest is higher and their creditors are much less patient.  They also live in their parents' basement, so they have no house to sell to get them out of trouble.  And most worrying, they haven't assumed responsibility for the mess they made and spend most of their time blaming other people rather than trying to fix it.