The small, forty-year-old cryonics industry offers indefinite low-temperature storage of at least your brain following death. In a well-organized cryopreservation, the medical team is right there when you die, and cooldown and infusion with cryoprotectant solution can begin immediately. The result is vitrification of tissue, especially brain tissue, to preserve the fine structure that stores the data of the mind. Then you wait, suspended, in liquid nitrogen in a dewar vessel, heading for an uncertain future in which the possibility of restoration exists. That possibility is what you are paying for, and it is the single most important difference between cryopreservation and all the other choices you have at the end of life. Those other choices offer only the certainty of oblivion, but for so long as the data of the mind exists, so long as there is continuity of preservation, then sufficiently advanced molecular nanotechnology and biotechnology will one day be capable of restoring you to life. In a world in which a small but growing number of people are striving to build rejuvenation therapies to defeat aging, and the timeline for that defeat is very uncertain, cryonics is the only available backup plan.
Personally, I don't see much uncertainty in the golden future of transcendent technology that lies ahead. It will happen. The uncertainties all lie in the timing of that technological progress, how long continuity of preservation and preservation organizations can be sustained, and most of all in arranging the slings, arrows, and final moments such that the medical team is in fact right there and waiting when you die. That last one is the hardest part, and will remain so until the laws on euthanasia become more civilized in more parts of the world. If we could be allowed to choose our time, then all cryopreservations could be well-run, minimizing tissue damage and cell loss, and be largely free from large and unexpected costs. Sadly that's all too rarely the case. Even people in very late life are surprised by their own final decline, and all too few make the serious effort to ensure that the unexpected is caught, or at least that it is going to happen in a location at which the cryopreservation organization can muster a very quick response. That it is illegal for people to help you in this situation through euthanasia is just the final indignity, a reminder that civilized and compassionate behavior on the part of those in positions of power remains a still-thin veneer.
What I wanted to talk about here is related to all of this, but not really discussed all that much in the cryonics community. I think it might be one of those things that is so taken as read in the core community of supporters that people don't put much thought into it. Cryonics organizations are non-profits with a membership structure: you pay a monthly or annual fee, and have a variety of options when it comes to ensuring funding for your ultimate cryopreservation, an event hopefully still decades away at the very least. Cryopreservation is in effect a form of surgery, plus other items, involving a group of medical and technical folk with specialized tools carrying out a procedure, and so the costs are similar to those of a surgical procedure - which works out to anywhere from $30,000 to $200,000 depending on the organization and the details of the arrangement. Most people opt to pay using life insurance, since a contract for even $200,000 is pretty cheap on a monthly basis if you are healthy and young, and a life insurance policy can be set up so that the mechanisms of payment will go into effect robustly on your death with no need for micromanagement at a time when you are unlikely to be capable of that effort.
However, this isn't a case of a transfer of funds today, where you see you need to pay $200,000, so you set up a policy for $200,000 and you are done. No. The cost of the cryopreservation agreement today is that $200,000, but that amount will rise with inflation. Thus you take out a life insurance policy that also grows with time. There are many varieties of growth policies, all using different models to try to keep up with inflation while still making a profit for the insurance company. Sometimes they will work, sometimes not, but the people involved in setting up these instruments are all pretty motivated by competition to try to adjust to keep up. Still, we are talking about trying to match the future inflated amounts of two very different things half a lifetime or more from now. If you look at the rule of 72, you'll see that even for plausible levels of inflation on the part of a government that more or less achieves the level of debasement of currency that it aims at, costs will double several times between youth and old age: it is not implausible to expect the $200,000 cryopreservation you signed up for to cost $800,000 four decades from now. If the US meanders into another period like the 1970s, the situation could be much worse than that. If rejuvenation biotechnology goes the way I hope it does, then the horizon and the financial uncertainty expands further. Not that you can't adjust along the way, but that is always going to be more expensive than just being right at the start. Given this, the smart thing to do is to make the life insurance policy larger than it has to be at the outset, especially since that choice costs little. Overfunding the policy shifts the odds greatly in your favor when it comes to the life insurance payout being larger than the cost of cryopreservation on the day that bill is due.
This matter of uncertainty in inflation and financial instruments is not the only reason to have a larger life insurance policy than the minimum needed. Consider that there are any number of things that can go wrong at the end of life, greatly increasing the costs incurred by the cryonics organization. Yes, once you and the cryonics technicians are in the same room, everything is practiced and under control, but before that point there are many ways to run off the rails. You could be in an inconvenient location, local government officials or family members could interfere and require legal efforts to deal with, flights might have to be chartered at short notice, and so on and so forth. Any one of these could easily balloon into a few tens of thousands of dollars today. If you look back through the history of cryopreservations in which the details have been made public, such as those published by Alcor, there are many cautionary tales, and more than a few cases in which everyone involved did the right thing and costly problems still occurred. If the hurdles put in place by chance or opponents are too costly for the cryonics organization to overcome, given the funding you have put in place, or that others can supplement at the time, then you won't be preserved. Cryonics providers will make absolutely the best effort possible, and again, if you look at the history there are many cases in which companies and volunteers have gone above and beyond to make a cryopreservation happen, but they won't damage or risk the sustainability of the entire organization for one person. Lines have to be drawn.
So, again, assume the worst, and when sorting out life insurance apply for more than the minimum needed to fund your cryopreservation. Twice the minimum is not unreasonable: nothing in life is certain, and it is better to be safe than sorry when being safe costs little. It is all about swinging the odds more in your favor. If the extra funds turn out not to be needed, then they can be directed to a charity, or to sustaining the cryonics organization, or its research efforts, or another worthy goal. Some people even set up forms of perpetual trust, another experiment with an uncertain chance of success, but which may lead to there being some personal funds to continue with in the case of restoration. Certainly from an immediate and practical point of view, all of the cryonics organizations advise in their materials that you overfund your policy, but they tend to say as much and move on. There's less in the way of accessible discussion out there that goes through the reasons as to why this is the case. Hopefully this small contribution helps.