If the title is not respected, they still have their art and gold. I think the real statement here is: have something that afterwards still has some value, which you can use to build upon. Other sources of wealth like money, will more like be gone when the state folds, or time goes on. Timeless wealthes are the way to stay rich over the ages.

For most of those 600 years gold was money.

Coins were money. Gold was just one of the materials they were made from. There also was copper, silver, and others. Raw gold alone was somewhat useful, but AFAIK usually not as valuable as local gold-coins. Usually trading something golden meant accepting some loss, like today.

And even then it sometimes works. Many (but not all) large Spanish land grants were respected in the US southwest/California after the Mexican/American war.

Of the foreign army gets expelled by a force that has zero interest in respecting whoever was there previously. At that point you might as well throw in the towel and open up a cheap Chinese buffet restaurant in a former mill town in upstate NY (or something like that).