Look at it in terms of years gained instead of lives lost.

Saving 28 lives gives them each 50 years at best until they die, assuming none of them gain immortality. That's 1400 man-years gained. Granting immortality to one person is infinity years (in theory); if you live longer than 1400 years then you've done the morally right thing by betting on yourself.

Additionally, money spent on cryonics isn't thrown into a hole. A significant portion is spent on making cryonics more effective and cheaper for others to buy. Rich Americans have to buy it while it's expensive as much as possible, so that those 28 unfortunates can ever have a chance at immortality.