If you ask those who are skeptical, disinterested, or even hostile towards work on the basis for rejuvenation therapies, many of them justify their positions with - among other items - a belief that rejuvenation is a far future possibility, not something that will arrive in their lifetimes. So why should they offer their support, given that they will not benefit? They'd rather leave it to the slow march of science, which most people seem to think just happens, a background process that runs without any outside intervention.
Firstly, this is a dramatically mistaken point of view. The first of the SENS-style rejuvenation therapies, the clearance of senescent cells, is presently in the clinical development pipeline in a number of startup companies. Forms of treatment will be available a few years from now via medical tourism, and the adventurous can already obtain many of the candidate drugs and try their own self-experimentation. The first class of rejuvenation therapy is imminent, not distant.
Secondly, even if it were true that rejuvenation is long way distant, why not help to build the infrastructure for a better world that will carry forward into a future that you expect not to be around for? People do that all the time in other parts of their lives, without the same sort of vocal rejection that all too frequently accompanies views on healthy life extension, a goal to be achieved through new medicine to treat the causes of aging. Why should longevity be any different? I think that this is another of the many ways in which people demonstrate a strange irrationality when it comes to aging and medicine.
This is what I call a 'meta-objection', because it's not really meant against rejuvenation per se. Rather, this meta-objection is usually raised after a long, drawn-out conversation between a rejuvenation advocate and an opposer. At the end of the debate, when the suspicion that rejuvenation is in fact desirable and may be feasible is starting to creep up into the opponent's mind, they resort to their final, desperate line of defence, the very last stronghold behind which their cognitive ease can still find shelter. If we all thought like that, no one would do anything to make rejuvenation happen, and consequently it would never happen, in anyone's lifetime, ever. We can either risk it and do all that is in our power to make rejuvenation happen sooner rather than later, or we can sit about and wait to become old and sick.
Besides, if rejuvenation is worthy goal per se, should you not help pursue it just because you might not reap the benefits? We hear all the time that we should take good care of the planet for the sake of future generations and be concerned about the kind of world we leave them with. Well, we can try to leave them with a world where ageing has been cured, so that those very future generations we seem to care so deeply about won't have to go through the plague of age-related diseases. If you have children, this should resonate particularly well with you. Old or young, they'll always be your children, and you'll always care for them, right? Without rejuvenation, they too will be condemned to decades of infirmity and suffering, and ultimately to an unnecessary death.
If rejuvenation could be achievable within the opposer's lifetime, they would have a glimmer of hope to hang on. And as they say, isn't it hope that kills us all? If they decided to accept this possibility, it would mean a lot of mental work, of the kind people generally dislike. First, there's the risk of disappointment. What if something went wrong, and rejuvenation didn't come in time for the opposer? They'd have spent a life hoping for something that never came. The thought isn't particularly nice. Second, there's a choice to be made between activism and 'inactivism'. In order for rejuvenation to become real, there's a lot of work to be done, not only in terms of research but also advocacy. Would the opposer be willing to do their part and spread the word, convince others of the worthiness of the cause, and take action to make it happen sooner? That's a lot of work, and there's no guarantee of success. They'd have to endure endless debates with sceptics, which could be quite taxing.
This is not all! Accepting the possibility that rejuvenation may become a thing within their own life, and that they may actually want it for themselves, the opposer is forced to seriously question their previous assumptions on ageing. This idea that ageing is bad for you and not desirable is a new thing, one they're not used to. They're used to accepting ageing, to think of it as a blessing that prevents the (imaginary) risks of eternal boredom, overpopulation, everliving tyrants, and a series of other sensible-sounding, but ultimately groundless excuses we've made up throughout history to cope with the sad truth of the grim descent into frailty, disability, and disease that precedes death. If they challenged their old assumptions on ageing, the opposer would be forced to conclude that ageing is a really bad thing - and what's worse, that really bad thing is coming for them, and their chances to avoid it are tied to a technology that may or may not come into existence depending not only on the progress of science, but also largely on how willing other opposers will be to challenge their own preconceptions on ageing.
This is where our opposer comes to the realisation that he or she would have to deal with all this trouble only if rejuvenation could happen within their own lifetime. If rejuvenation was so far into the future that the opposer was granted to die before they could ever benefit from it, all of these troubles would just disappear. 'Yes,' the opposer would say, 'maybe defeating ageing is feasible and perhaps even desirable, but it's not doable within my lifetime. So, there's no need to concern myself with it.' It's so easy, isn't it? The easiest way of 'solving' a problem is pretending it isn't there to begin with. You can keep repeating to yourself all the lies about why ageing would be a good thing, until - as it's often the case - they start to feel true and make you feel good.