]They have kindly, wealthy relations belonging to the gentry, who can help them out. In that respect, they are very privileged as they can be secure in the thought that they will never fall into destitution.

Sir John could keel over tomorrow. Or he and his wife could be thrown into a ditch while out in their carriage. The Dashwoods are not likely to meet with so fortunate a situation again. Mr. Knightley surmises about the Bateses who depend greatly on the charity of friends and neighbors: they are likely to sink further still. While I am looking at a worse case scenario, a similar fate happening to the Dashwoods is not beyond the realm of possibility. Ending up on the cusp of poverty needs for only one particular thing to go wrong. :)