My gut estimate is that the chance is somewhere in the 1-10% range. I've been thinking about it for around 5 years. Part of why that number is so high is the relative lack of coherent and nuanced counterargument that demonstrates the critic at least understands the issue (not just one aspect, but the whole huge convoluted topic) well. I may end up becoming such a critic myself, eventually, but so far things aren't looking so bad for cryonics.
It is true that chances can't just be "non-zero" and be rational, nor simply based on faith, because that's basically Pascal's Wager. However I think my 1-10% gut feeling is something that I could probably be talked out of if it were really arbitrarily low like people keep assuming.
Assuming that probability range, I think selling to ordinary people is pretty defensible at $50k-$500k rates, because we already spend around $5M to avoid accidental deaths via regulatory tradeoffs. If it is lower (0.1% say) and yet still not arbitrarily low, we would then need to restrict to either very rich or very desperate people (where the ratio of marginal utility of life to marginal utility of a dollar differs significantly from the norm). Arbitrarily low chances literally on level with egyptian mummification or worshipping a random god is definitely not something that should be sold to anyone (except as a novelty maybe).
Note also that cryonics storage cost is influenced by economies of scale, so mass-produced cryonics is likely to be a lot less expensive per person than the cost you see on the market today. If you could seriously measure a non-arbitrary 0.01% it wouldn't necessarily be impossible to justify even on the mass market and even to relatively death-complacent people -- it would just have to be very cheap for them. Granted, gut feelings are hard to calibrate well to reality at such extremes (hence lottery tickets) so I'm not going to seriously argue that, I'm just saying this to give you a feel for why I think there's a need for fairly strong counterargument before you can reasonably take the position that cryonics is just innately bad/fraudulent business.
I also anticipate various positive externalities from the cryonics business, such as sooner (eventual) development of suspended animation of the damage-free variety, which has potential to save a lot of lives and spare a lot of suffering. These too should be accounted for as part of a robust criticism.
It is true that chances can't just be "non-zero" and be rational, nor simply based on faith, because that's basically Pascal's Wager. However I think my 1-10% gut feeling is something that I could probably be talked out of if it were really arbitrarily low like people keep assuming.
Assuming that probability range, I think selling to ordinary people is pretty defensible at $50k-$500k rates, because we already spend around $5M to avoid accidental deaths via regulatory tradeoffs. If it is lower (0.1% say) and yet still not arbitrarily low, we would then need to restrict to either very rich or very desperate people (where the ratio of marginal utility of life to marginal utility of a dollar differs significantly from the norm). Arbitrarily low chances literally on level with egyptian mummification or worshipping a random god is definitely not something that should be sold to anyone (except as a novelty maybe).
Note also that cryonics storage cost is influenced by economies of scale, so mass-produced cryonics is likely to be a lot less expensive per person than the cost you see on the market today. If you could seriously measure a non-arbitrary 0.01% it wouldn't necessarily be impossible to justify even on the mass market and even to relatively death-complacent people -- it would just have to be very cheap for them. Granted, gut feelings are hard to calibrate well to reality at such extremes (hence lottery tickets) so I'm not going to seriously argue that, I'm just saying this to give you a feel for why I think there's a need for fairly strong counterargument before you can reasonably take the position that cryonics is just innately bad/fraudulent business.
I also anticipate various positive externalities from the cryonics business, such as sooner (eventual) development of suspended animation of the damage-free variety, which has potential to save a lot of lives and spare a lot of suffering. These too should be accounted for as part of a robust criticism.