Roko:

Perhaps I should make an analogy: would it be rational for a medieval peasant to refuse cryo where revival was as a billionaire in contemporary society, with an appropriate level of professional support and rehab from the cryo company?

This is another issue where, in my view, pro-cryonics people often make unwarranted assumptions. They imagine a future with a level of technology sufficient to revive frozen people, and assume that this will probably mean a great increase in per-capita wealth and comfort, like today's developed world compared to primitive societies, only even more splendid. Yet I see no grounds at all for such a conclusion.

What I find much more plausible are the Malthusian scenarios of the sort predicted by Robin Hanson. If technology becomes advanced enough to revive frozen brains in some way, it probably means that it will be also advanced enough to create and copy artificial intelligent minds and dexterous robots for a very cheap price. [Edit to avoid misunderstanding: the remainder of the comment is inspired by Hanson's vision, but based on my speculation, not a reflection of his views.]

This seems to imply a Malthusian world where selling labor commands only the most meager subsistence necessary to keep the cheapest artificial mind running, and biological humans are out-competed out of existence altogether. I'm not at all sure I'd like to wake up in such a world, even if rich -- and I also see some highly questionable assumptions in the plans of people who expect that they can simply leave a posthumous investment, let the interest accumulate while they're frozen, and be revived rich. Even if your investments remain safe and grow at an immense rate, which is itself questionable, the price of lifestyle that would be considered tolerable by today's human standards may well grow even more rapidly as the Malthusian scenario unfolds.