One person donates 500 dollars to charity, of which a small amount provides a bunch of rice to hungry poor people in africa. They live instead of dying, and have more kids who are still hungry.

Another person is a douchebag early adopter of the cell phone, spends his 500 dollars on that the latest tech gadgets and shows off to people. Years later medical researchers develop a method involving a cell phone that can be used to cheaply diagnose diseases by people in africa with minimal training. The suffering of millions is alleviated.