One of the hardest books to read and see that for a pittance the world could eradicate several types of horrific diseases or drastically improve large numbers of lives, through simple targeted investments, and yet it never happens.
Here's a more personal example. After reading the book, a friend who made a mint in the oil industry bought four mobile drilling rigs, fitted them for digging water wells, paid to ship them to a state in I can't remember which country, but it was a poor one in Africa, where he hired a crew to run the operation and dig wells for free. He said it was a nightmare of red tape to operate, but wells got dug and people got fresh water that used to get dirty water.