Risk aversion arises when you would get a high marginal utility of wealth in future states in which you are relatively poor.
Risk aversion can be demonstrated even in trivial cases where you offer people a certain payout of $10 or a 50% chance of getting $20. I don't think it's about high marginal utility of wealth in certain future states.
Cryonics is not at all like insurance: insurance is about paying to protect yourself from a small chance that a bad thing will happen. Cryonics is about paying to get a small chance that a good thing will happen. It's much more akin to a lottery (as Vaniver already pointed out).
Risk aversion generally occur when your subjective utility with respect to some quantity X is monotonically but sublinearly increasing.
In most economic analysis X is generally considered to be money, but it can be really anything else, including years spent in utopia.
Every so often, I see a blog post about death, usually remarking on the death of someone the writer knew, and it often includes sentiments about "everyone is going to die, and that's terrible, but we can't do anything about it have so we have to accept it."
It's one of those sentiments that people find profound and is often considered Deep Wisdom. There's just one problem with it. It isn't true. If you think cryonics can work, as many people here do, then you believe that people don't really have to die, and we don't need to accept that we've only got at most about a hundred years and then that's it.
And I want to tell them this, as though I was a religious missionary out to spread the Good Word that you can save your soul and get into Christian Heaven as long as you sign up with Our Church. (Which I would actually do, if I believed that Christianity was correct.)
But it's not easy to broach the issue in a blog comment, and I'm not a good salesman. (One of the last times I tried, my posts kept getting deleted by the moderators.) It would be a lot better if I could simply link them to a better sales pitch; the kind of people I'm talking to are the kinds of people who read things on the Internet. Unfortunately, not one of the pro-cryonics posts listed on the LessWrong wiki can serve this purpose. Not "Normal Cryonics", not "You Only Live Twice", not "We Agree: Get Froze", not one! Why isn't there one? Heck, I'd pay money to get it written. I'd even pay Eliezer Yudkowsky a bunch of money to talk to my father on the telephone about cryonics, with a substantial bonus on offer if my father agrees to sign up. (We can discuss actual dollar amounts in the comments or over private messages.)
Please, someone get to work on this!