I recall from TSP that RW claimed the house was their livelihood as well as their home. There was never any mention (from memory) of them having any sort of normal jobs.
I'm finding this whole 'reveal' so interesting - having read TSP (and recently seen the film, although not read any of her other books) something did always seem a bit off. I always felt as though their story about the financial ruin and losing the house was something more than described, as it just didn't make sense, and there was zero ownership of the situation from their point of view.
Having been through my own mid life "comeuppances", the real OPPORTUNITY of them is that they provide us the chance to own our part in how our life has turned out, take stock and grow as a person. I didn't get any sense from their journey that they did any growing at all - there was no ownership about what decisions in their life had brought them to this crisis point of being in their 50s and supposedly homeless and penniless.
Coming out of the film, and it having been many years since reading TSP, it was noticeable that the story is focused entirely on them. None of the other characters have any flesh to them. Everyone else is totally incidental, and the female walker they encounter who joins them at one point late on, but then just randomly wanders off, just didn't work in film. There's a vaguely emotional point at the end, and then the credits roll... although the narrative takes you on a journey, it really is just a geographical one from A to B, and not one of their growth as people.