This is something that was added to another post (about the NHS) it wasn't me that wrote it but I think it sums up pretty well why it's right that we don't or shouldn't routinely do the sorts of major and expensive surgeries/ interventions on the elderly as we do on the young.
"there is a lot of benefit to be had around thinking about what the real outcomes and goals of healthcare are as people age. It's not just about the money either, it's about what makes for good care. Personally, I think the money element isn't really the point at all, it's just a result of the more basic problem of trying to work against the natural, and inevitable decline of the body, which always in the end has to fail to deliver.
If we imagine that somehow we can fend off death inevitably, or medical interventions will really put us back to feeling a lot better, we will tend to take one approach to medical decisions. That's how we think with kids most of the time, almost until death is imminent - old age is too far away for natural death to be a consideration, and if disease is beaten there may be a really high chance or good quality of life, a long life full of human experiences, and a real improvement in condition. There is often good reason to go full on with medical interventions, even if some are invasive and involve suffering.
When that's the reality, an 80 year old suddenly faced with medical decisions might make very different decisions than a 20 year old.
The usual approach is to let people make these decisions themselves, which theoretically is sound, but because culturally we don't really deal with the realities of inevitable decline and death,we get people at 75 or 80 making the kinds of decisions that people at 20 might make. Often medical staff don't really help them understand the realities around the outcomes of the treatments they are proposing. We have over the last half century or so added about a decade on to people's lifespan, but it isn't necessarily a healthy decade - often it's beset by illness and poor quality of life."