I'm surprised nobody has made the point that "death" is not a binary thing - it is a progression. If we consider a scale where "1" is alive (breathing, heart beating, higher brain functions working, etc) and "0" is when your brain has been unambiguously destroyed, we have a probability distribution of whether a person can be returned to "1".
At one time if someone left "1" (e.g. heart stopped), that was pretty much it. Now we can often recover someone whose heart has been stopped for several minutes with little to no long term damage through medical intervention. A cryonic procedure pushes a person to a place on the scale where the probability distribution provided by current technology is a big fat zero. There is some hope that as technology advances that probability distribution will look favorable to the those frozen. We're pretty much just guessing about that last part though.
Wikipedia's article on clinical death[0] seems to go into a lot of the boundaries involved and is worth a read. I have read about information-theoretic death before but forgotten the term. I first heard about Alcor quite along time ago (10-15 years), and have considered signing up, but haven't so far.
As much as I'd love to cheat death I can't get over the feeling that having myself frozen would be a selfish and arrogant act. I worry that the world will continue to struggle with limited resources and wonder how people will feel if the technology to revive cryopreserved people becomes available but it's a struggle to provide the unambiguously living with food, water and shelter. That said, I find it difficult to fault those who choose to try to escape mortality. I would be interested to hear how people justify it from a resource allocation perspective.
Perhaps we'll figure out how to do mind uploading and solve the problem that way? That's a whole other rabbit hole though, and there's plenty of potential for that to suck[1].
At one time if someone left "1" (e.g. heart stopped), that was pretty much it. Now we can often recover someone whose heart has been stopped for several minutes with little to no long term damage through medical intervention. A cryonic procedure pushes a person to a place on the scale where the probability distribution provided by current technology is a big fat zero. There is some hope that as technology advances that probability distribution will look favorable to the those frozen. We're pretty much just guessing about that last part though.