What does it mean to eat crab with vinegar?

But my understanding should be: either someone is stingy or the family is poor.

Crabs are not cheap now. You can afford crabs, but you don't need your own vinegar or buy vinegar, but borrow vinegar, which shows that you are very stingy.

But more than a decade ago, crabs were everywhere, and they were very worthless. Rural people only eat crabs when they have nothing to eat. Moreover, eating crabs and even vinegar is borrowed, which means that it is quite poor.

Do you think this explanation is reasonable? . . . . .