I know it really sounds cheesy, but I did feel a duty to try to tell the stories of people who couldn't speak for themselves.
For success, the author must make the reader care about the destiny of the principals, and sustain this anxiety, or suspense, for about 100,000 words.
I'm a big fan of huge populations of people, so you'd think with 300 million people in the country, you don't even have to please 1% to be phenomenally successful.