If someone is arguing that life is a net bad, and that this means that cryonics is a poor investment, then I will at least concede that their arguments are consistent(even if them being alive to make those arguments is not). But I don't think that argument is being made. Arguing from a tiny possibility of a very bad outcome is playing very obviously to human emotional biases, and the result almost always needs to be discounted significantly to account for the low probability.