Developed societies in the 21st Century have started to break down in certain ways because we live in "the long run" discounted by people who made bad decisions for us when they ran things decades ago. I've seen this happen in cryonics organizations, even though, as Roko speculates, you'd expect that the members who have a stake in cryonics' success would insist on better performance.

Absolutely true. The cryonics meme spread widely is more sustainable -- and thus more useful -- than if only a few people have it.

Not to mention the fact that it could raise the sanity waterline quite a ways. That is a benefit that would be of lasting value (and perhaps steer us clear of a few existential risks) regardless of whether cryonics works.

Obviously if we knew cryonics wouldn't work it would not raise the sanity waterline to pretend otherwise -- but the fact is that we don't know any such thing. It is a quite valid assumption that it will work, as far as we can tell. And the cheaper cryonics is, the less sane the refusal to consider it becomes.