On probability it'll work:
I haven't done much detailed research. "Cryonics works" is the default given the history of medicine and what Alcor says; there could be a flaw or an outright lie in the case for cryonics that makes it deviate -I am not an expert. But the case against cryonics is non-existent. Why would experts not debunk it, if it were false?
On cost:
Robin Hanson has a calculation saying it's worth it . I haven't checked. Morendil argues that the cost (a few $100 per year) is very low relative to other expenses. Even if both arguments are false, cryonics still looks developed-country-cheap.
It's a bad strategy for someone who'll die soon, because they can't get life insurance. Cryonics is cheaper when young and healthy.
On opportunity cost:
Research time doesn't look all that limited. (If it does, why not sign up for cryonics with as little research as possible?) I'm not sure what other costs you're talking about.
Life extension is a very good idea, yes. But it's not incompatible with cryonics (unlike mummification and graveyard eggs); in fact it helps, because cryonics is best if you deanimate late (cryonics improves with time, and the longer your life expectancy the cheaper insurance gets).
If life extension techniques look so incredibly good that you put every cent and second in them, sure, go ahead and be a hero - but that applies to every expense, not just cryonics.
It's a bad strategy for someone who'll die soon, because they can't get life insurance. Cryonics is cheaper when young and healthy.
Life insurance is more expensive than paying in cash. If that weren't true, no one could make money selling life insurance. Yes it amortizes the cost over time, and amortizes the risk over the population but that does not reduce the cost of it. The opportunity cost of cryo-preservation is the same whether you buy insurance or not.
From Mike Darwn's Chronopause, an essay titled "Would You Like Another Plate of This?", discussing people's attitudes to life:
Conclusion, graphs, and references in article. As usual, I recommend reading Chronopause.com as Darwin has many good articles; to quickly link a few: