A world in which people who sign up for preservation avoid death if and only if they're lucky enough to have signed up after, say, 2030, feels weirder than a world where the rational are rewarded, the irrational punished

It feels weirder, but has many precedents. Many 'bubbles' can be profitably interpreted as people being 100% correct about their vision of the future - but messing up the timing (see http://www.hoover.org/publications/policy-review/article/5646 and http://www.economist.com/news/finance-and-economics/21575737-lessons-americas-long-history-property-booms-betting-house for examples). I used this in another comment, but consider the case of an investor in the ill-fated Pets.com: was the investor right to believe that Americans would spend a ton of money online such as for buying dogfood? Absolutely, Amazon is a successful online retail business that stocks thousands of dog food varieties, to say nothing of all the other pet-related goods it sells. But the value of Pets.com still went to ~0. Many startups have a long list of failed predecessors who tried to do pretty much the same thing, and what made them a success was that they happened to give the pinata a whack at the exact moment where some cost curves or events hit the right point. (Facebook is the biggest archive of photographs there has ever been, with truly colossal storage requirements; could it have succeeded in the 1990s? No, and not even later, as demonstrated by Orkut & Friendster, and the lingering death of MySpace.) You can read books from the past about tech visionaries and note how many of them were spot-on in their beliefs about what would happen (The Media Lab was a good example of this - I read it constantly thinking 'yes, you were right, for all the good it did you' or 'not quite, it'd actually take another decade for that to really work out') but where a person would have been ill-advised to act on the correct forecasts. Or look at computers: imagine an early adopter of an Apple computer saying 'everyone will use computers eventually!' Yes, but not for another few decades, and 'in the long run, we are all dead'.

If cryonics turned out to be worthless for everyone doing it before 2030 while perfectly correct in principle and practical post-2030, it would simply be yet another technology where visionaries were ultimately right despite all nay-saying & skepticism from normals but nevertheless jumped on it too early.

When a knife drops, a fraction of a second divides a brilliant save from an emergency-room visit. They don't call it the 'bleeding edge' for nothing.