I don't think the choice is as simple as choosing cryonics or ignoring life extension completely. I am very interested in the idea of life extension, but so far what civilization has achieved in those terms is relatively modest, given that the oldest person to ever live only lived to 122, and I probably can't hope to even get to that. I would be absolutely thrilled to be wrong about this.
What makes me hesitate about cryonics is that it is so speculative. Perhaps it is possible to reconstruct a living brain from a cryogenically frozen one. However, I would want to have some expectation that this was so. To give an example, the ancient Egyptians believed that mummification allowed one to continue to live. However, as they removed the brain entirely, their strategy for life extension is not one I think you would be interested in investing in (even if no one was saying you also had to believe in Horus,Isis, Osiris, et al). Cryonics seems a much more plausible revival strategy than ancient Egyptian mummification to me, but I also think restricted caloric diets are more plausible than cryonics (given that this has been shown to work on a wide variety of species, even if humans aren't one of those). You may think that restricted caloric diets could never possibly extend people's lives as much as cryonics, but I think it is currently impossible to estimate the additional lifespan of a person successfully revived from cryonic extension. Your assumption, I'm guessing, is that this number would likely be large due to improved future technology. Once again, I think this is a huge assumption, and given the large number of things I could conceivably try, I think the best bet would be to first figure out, to the greatest degree possible, the answer to the following three questions:
And I'm not saying that a person couldn't choose more than one strategy of life extension. For example, there's no reason that a person couldn't choose caloric restriction and cryonics. The only problem with choosing one or more of these (and other) strategies is that you don't just have the possible benefits, but the very real costs. And the more strategies you choose, the more of those costs you incur (even ignoring strategies that would be mutually incompatible). With caloric restriction, an obvious cost would be that it would take more time and effort or money to stick to the low calorie, high nutrient diet required (you probably won't find many restaurants or vending machines that serve the appropriate foods in the appropriate portions, so the only two choices would likely be to do all the cooking and meal planning yourself, or to have your own personal chef who is well-versed in such a diet). Also, if you do not have sufficient self-control, you would probably have to have someone hovering over you, forcing you to eat the right foods (significantly detracting from your quality of life and likely also a blow to your finances). For cryonics, the obvious cost is the non-trivial amount of money it would take. Maybe it would be better to find a way to store information about the brain in a computer until it could be restored. Maybe your brain would be better preserved in a jar of formaldehyde (although I'm hoping for the sake of cryonics customers that this isn't so, some of those who had their brains preserved for science might then gain an unexpected benefit).
So no, I don't think the success rate of not-cryonics is a guaranteed zero. I don't even think the future success rate of cryonics is a guaranteed zero, and you could convince me with more evidence that it is not an almost-certain zero. I would consider the successful revival of non-human animals of increasing complexity through cryonics a great first step to proving its viability. And I need more evidence of the expected benefits only because I have ample evidence of the expected costs (nobody is saying cryonics is free). Opportunity cost means that I should make choices not only with the consideration of what that choice might gain me, but also what passing up my other choices might cost me. That's why I think it's a better strategy to give money to life extension research now than save up to give to cryonics specifically to freeze me.
I hope that helps to clarify my thinking on this. I am wondering, what experimental evidence in favor of cryonics do you find most compelling? Are there other life-extension strategies you have considered?
EDIT: Curses...my HTML tricks will do me no good here (goes off to search for message board markup tags...)
EDIT: Yay! Fixed! Thanks for the help, @Mixed Nuts and @nsheppard!
You may think that restricted caloric diets could never possibly extend people's lives as much as cryonics, but I think it is currently impossible to estimate the additional lifespan of a person successfully revived from cryonic extension. Your assumption, I'm guessing, is that this number would likely be large due to improved future technology. Once again, I think this is a huge assumption, and given the large number of things I could conceivably try.
What things could you possibly try in the present that couldn't also be used in the future on revival? ...
From Mike Darwn's Chronopause, an essay titled "Would You Like Another Plate of This?", discussing people's attitudes to life:
Conclusion, graphs, and references in article. As usual, I recommend reading Chronopause.com as Darwin has many good articles; to quickly link a few: