The problem with this argument is that it hinges on a flawed assumption. The assumption is that we dare taking any risks at all only because we know that in a few decades at best we’re going to be dead anyway. Why do you take a plane for a holiday at the Antipodes? Because you’re going to die anyway when you’re old. Why do you go on a rollercoaster ride? Because the reaper would get you sooner or later anyway. Why do you go out without an umbrella even though it looks like it might rain? Because pneumonia would cut your life only a few decades shorter. Note that this argument also answers the age-old question, ‘Why did the chicken cross the street?’ Because YOLO.
This is not how smart people (or chickens) think. The question is one of magnitude of benefits and risks of a certain course of action. Consider the case of John, 40 years old, taking a plane from New York to Madrid for a two-week holiday. There is a chance the plane might fall into the Atlantic Ocean during the flight, in which case John would die. The chance isn’t very big, but it’s not zero nonetheless. If the plane doesn’t fall, then John gets his holiday (the benefits); however, if the plane falls, not only does John not get his holiday, but he also loses his life. At age 40, John isn’t exactly a youngster any more, but he does have some 40 years of life left, though. While the perceived value of the holiday and the remaining 40 years of life are subjective, it is quite reasonable to say that two weeks in Madrid aren’t worth losing 40 years of life. After all, John could do all sort of things with that kind of time, all equally (if not more) rewarding than spending two weeks in Madrid. Why did John take that plane, then? Maybe because, should he die, he would lose ‘only’ 40 years? Maybe he thinks it’s well worth risking 40 years of life for two weeks in Madrid; perhaps, if he was risking 80, or 90, or 120 years, he would think twice before hopping on that plane.
Hardly so. The reason John decided to took the plane was quite likely unrelated to how long he thought he had left to live at that point. Rather, John concluded that the risk to die in a plane accident was insignificant. Had John known that the plane had a 50% chance of falling into the ocean, do you think he’d have taken it? Most likely not for the sake of a leisure trip. Conversely, assume the reason John needs to take that plane was that he is escaping from a country torn by civil war, where he has an 80% chance of dying every day. Suddenly, that 50% chance of the plane falling doesn’t sound so bad any more; he’d better take a one-shot 50% chance of death over a daily 80% chance. They’re both sucky, but the first option is far better than the second.
Another interesting implication of this objection is that, if you have little time left to live, you might indulge in risky behaviour more than normal, because you don’t have much to lose. This does happen: Terminally ill patients who decide to try sky-diving are not unheard of, although I don’t have any reliable statistics showing how frequent or rare this is. However, old people—even old enough to be considered terminally ill with ageing—usually don’t take more risks, big or small, than young people. In fact, even though they only have one or two decades left to live, they may well decide to stay at home on a rainy day to avoid catching a cold. Why is that? Quite possibly because they know that, at their age, a cold can easily turn into something more serious and life-threatening. Their chances of losing their life are higher than young people’s, but they have only quite little life left to lose. Nonetheless, they generally prefer to avoid any risk that might take their remaining life away from them, however short that life may be.
The difference in behaviour between old people and terminally ill patients might be explained by their perception of their respective remaining lifespans. Terminally ill patients generally know quite accurately how much they have left to live; a doctor has probably told them they have six months or a year. Old people may know that they don’t have much left to live, but they generally don’t know how long exactly. I suppose that, in the case of old people, it may appear as if their fate is not yet set in stone, as opposed to the case of terminally ill patients.
Be as it may, it seems quite clear that people tend to value very much the life they have left, however long or short that may be; they might risk it only if they valued the payoff more than their remaining life, or if the magnitude of the risk was negligible. If ageing was defeated, you could live ‘forever’; thus, every time you stuck your nose out of your door, you might miss out on eternity because of a careless driver or a huge weight loosely hanging from a crane. The potential loss would be enormous every time, but the risk of this loss would be ridiculously small every time—possibly getting smaller and smaller as time goes by, because we get better and better at preventing accidents and improving our safety measures. It seems apparent that there would be no reason to go paranoid over negligible risks just because of their very high potential loss; some people might overworry, but I would go so far as to say that these would be pathological exceptions, certainly not the norm.
Objections to living ‘forever’
Objections to rejuvenation
All answers in short