Digging in you could learn the actual effects when a country defaults or even makes real effort to avoid defaulting. However, failing to understand the details is not protection. So, the point is you can directly see a major problem getting worse.
Further, that was simply a random example. Substitute the global obesity crisis and the point stands.
Without context, this is meaningless. Most people lack the context to understand what National Debt even is, let alone how it works in an economy; for proof of that, look at all the people who are, to all appearances, utterly convinced that China can "repossess" massive tracts of land because it "owns" some of our debt. The utter confusion of ideas required to hold such convictions is beyond me, but such notions are out there, and quite potent in certain circles.