Actually, when you put the argument for cryonics like this, it kind of sounds like a version of Pascal's Mugging. Perhaps we could call this: Pascal's Benefactor.
As MixedNuts pointed out, it's Pascal's Wager - yet you have a point. Putting the argument like this might cause the Pascal's Wager Fallacy Fallacy (which is still one of my favourite posts on this site).
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: