The reason I'm not currently persuaded that cryonics is worth it for me is that it is one of quite a large number of things I could do that have a very low probability of a very large benefit. With cryonics there's a high level of uncertainty around both the probability of success and the magnitude of the benefit. I don't have the time or resources to sign up for all such things, nor do I currently have the inclination to devote the resources to investigating all of them thoroughly enough to narrow the uncertainty. Cryonics is hovering around the level where additional research may seem worthwhile whereas, say, buddhism is not. It hasn't quite crossed the threshold yet however.