Natto is clearly a prime example of desperation food: "Oh, crap! All the soybeans have gone moldy, the crops have failed, and it's either eat the moldy soybeans or starve to death."
Ditto for the large escargot snails in Burgundy (I've observed wild escargot on my visits there). Nobody would consider eating them except in a do-or-die situation.
And especially ditto with Epoisses and related stinky cheeses. These are clearly cases where the cheese-aging process went wrong, but the people involved were too desperate for food to throw the spoiled goods away.
The first human consumption of oysters had to be a similar dire circumstance. In the case of raw oysters, they were out of cooking fuel as well.
Add sea cucumbers to that list.
One common thread in all of these disgusting eat-or-die foods is that later on they said, "Gee, we didn't die. We'll have to classify this as a 'delicacy'."