If Will's probability is correct, then I fail to see how his post makes sense: it wouldn't make sense for anyone to pay for cryo.

Similar to what I think JoshuaZ was getting at, signing up for cryonics is a decently cheap signal of your rationality and willingness to take weird ideas seriously, and it's especially cheap for young people like me who might never take advantage of the 'real' use of cryonics.