I'm very curious why you think 5% is a realistic estimate of the probability of cryonics working

I don't have a particular opinion on that. It's just the sort of figure I've seen from people in favour of cryo — that is the chance they are betting on, not a lottery jackpot. I am not signed up and am not planning to, despite having a sufficient pile of money. At the same time, I don't think the whole cryo movement is misguided either. It's an idea that should be pursued by those with the motivation to do so, both by freezing bodies now and researching preservation and revival methods.

I also don't have a particular opinion about how soon a singularity may happen (or a global extinction). For those who think that one of those is very likely to happen before they need cryo, cryo is also not a good bet. At least, they might want to keep their cryo funding in a more liquid form than an insurance policy.

So some of that probability will have to be spent on you not dying in a way that makes cryonics impossible, or on the cryonics company not going bust, or on there being no unexpected legal obstacles, etc). If you want to sell me on cryonics, this is what you will have to sell me on.

Yes, those are real concerns that anyone contemplating signing up, or urging other people to, has to assess.