Do you know their entire financial strategy or are you making a judgment based on assumptions?
There’s a form of reverse mortgage financing called, I think, a viatical, which covers that kind of situation. You get a wad of money, you keep the house till you die then the house becomes the bank’s.
Someone I work with did this. I hear her complain they have no money nearly every day so I assume they are a bit tight on funds. I could be wrong. Maybe I am too frugal.
If you can buy a new house and figure out a way to reduce your future monthly financial burden that is a good thing. However, listening over the walk I also hear her mortgage almost doubled and now has a new 30 year mortgage with 29-ish years left. To me, this sounds like a recipe for the poor house.