To me, the most relevant reason for not saving for cryonics mentioned here is that the success rate of cryonics is effectively zero at present.
Effectively unknown more than effectively zero. The latter makes it sound like you're expecting revivals to have already happened to demonstrate that it works. Or that you have some other positive information that allows you to conclude that people cryopreserved today will never be revived.
Well, I do think that someone has to be revived to demonstrate it works. This is not the same as saying that cryonics as it is practiced today couldn't work. Something can still work even if it hasn't been demonstrated, but to be demonstrated to work, it has to have already been done. However, I understand why you might want to try it even if it hasn't been demonstrated, given the potential for benefit.
So I still say that the success rate is zero at present, but this number has the potential to go up in the future. I do not equate success rate with probability of success. The probablility of success is unknown.
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: