> it's much more liieky a country will default or fal ito chaos (5 countries nearly did in 2011 during the European debt crisis) than the internet suddenly ceasing to exist or being broken up.

There are countries for which that may be true, but there are other countries with currency to hedge against those events.

When bad things happen, sometimes capital controls are introduced. This may restrict the ability for people in that country to purchase foreign currencies. Even in developed countries such as Iceland.

A small country defaulting isn't global destabilization.