It could also be a revealed preference that they don't like life enough to give their fate completely into the hands of unknown future people, or simply that they don't think the probability of successful cryonics + a good future is high enough to justify the costs.
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: