The average fellow in the street thinks that helping people to live longer is a bad idea, and usually expresses some combination of the Tithonus Error (the misapprehension that life extension technologies would make you live in increasing frailty, rather than extending youth) and the modern mixed package of environmentalist / classist / Malthusian / conservative beliefs on wealth and privilege: that equality should come by tearing down those at the top and halting progress, that there are too many people in the world, that any sort of increased consumption is evil, that changing anything to do with aging is bad.
This is the major challenge for the future development of means to extend human life - that most people reject it, even at their own cost, even when their beliefs about the way the world works are easily shown to be false: there is no overpopulation, only waste and corruption; stopping progress and trying to impose equality inevitably leads to something like the economic ruins of the old Soviet Union; Malthus was wrong in his time and still wrong now; and so forth.
Here is an educator's point of view, from one more embedded in the culture that rejects progress than most:
Our minds are perhaps hardwired to interpret the world in terms of simplistic patterns (like "haves" and "have nots"), but that does not mean it is an accurate representation of reality. Education should challenge our preconceived ideas of the world and dogma.
When I teach the weeks of my course on aging and life extension these points become most salient. I am always struck by the fact that (a) very few students understand that chronic diseases are the leading cause of death in the world, and (b) that chronic disease is a problem for both rich and poor countries, and (c) that people in poorer regions of the world actually age, and that this can cause them to experience suffering, disease, a decline in income, etc. I could go on.
Here are actual comments (I am paraphrasing from memory) I have heard students and others express when discussing population aging, global health and a Darwinian approach to medicine: "Old people should die sooner of disease so younger people can get a job". "A cure for cancer already exists, but Big Pharma makes more money off of cancer than curing it". "Wouldn't it be boring being alive longer and thus being married to the same person for longer?" "We shouldn't modify the rate of aging as it is unnatural". "Why don't we just spend all health research money on saving children and forget about helping those who are lucky enough to have lived a long life?" "Slowing human aging will destroy the planet".
Such sentiments are common, and part of my research involves trying to understand why people have such attitudes, and how one can help people come to critically examine such attitudes. The students that I encounter who have strong convictions that the world is overpopulated, and that the future of the planet is a bleak one because of population growth, typically have little knowledge of demography.