Though he had little formal education, Andrew Carnegie grew up to become one of the wealthiest men in the United States. He began to build his fortune by making wise investments in oil and other industries. By the late 1800s, Carnegie had founded a new business, the Carnegie Steel Company, which revolutionized steel production in the U.S., making it easier and faster to produce quality steel. He sold his business in 1901, embarking on a new philanthropic career that continued until his death. He founded Carnegie-Mellon University in 1904 and funded the building of 2,800 libraries across the country. In all, he donated an estimated $350 million of his fortune to charities and institutions. 

Best known for his quote:     

Man does not live by bread alone. I have known millionaires starving for lack of the nutriment which alone can sustain all that is human in man, and I know workmen, and many so-called poor men, who revel in luxuries beyond the power of those millionaires to reach. It is the mind that makes the body rich. There is no class so pitiably wretched as that which possesses money and nothing else. Money can only be the useful drudge of things immeasurably higher than itself. Exalted beyond this, as it sometimes is, it remains Caliban still and still plays the beast. My aspirations take a higher flight. Mine be it to have contributed to the enlightenment and the joys of the mind, to the things of the spirit, to all that tends to bring into the lives of the toilers of Pittsburgh sweetness and light. I hold this the noblest possible use of wealth.