Investment and sociological acceptance seem to me separate from the purely physical and biological aspects. For example, I am signaling optimism about the future very strongly by signing up for cryonics. Even an extremely low probability rating for cryonics working would not change this fact.

But in any case, the specific proofs needed for at least some guarded acceptance in physics and biology are already available. We know cells survive in large numbers, memories are structural (not dependent on electric fields), and vitrification limits damage (to the point that a kidney can survive in working condition). If you want to be a scientific skeptic of cryonics you need to be begin as literate of these facts and refer to reasons why you are still skeptical.

The demand for reanimation of a whole human or complex animal is far in excess of what is necessary to prove this as a good bet based on physical and biological data. The cost of ignoring the evidence in favor of cryonics that can accrue before that particular demonstration is vastly disproportionate to the cost of a false positive.