Why did Carnegie become a philanthropist?

Carnegie himself had been born into a very poor family, and had always been very grateful to the people who provided opportunities to educate and develop working boys like himself . Even at the time, he vowed to provide the same help to others if he should ever become rich enough to do so. He indeed started doing this long before becoming a full-time philantropist around the turn of the last century. As early as in 1860, he stated that he would never use more than $ 50,000 a year (in today's money, about $ 1 million a year) as a salary for his own needs, using the rest of his income for 'benevolent purposes'.He had also written about his views on social subjects and the responsibilities of great wealth in Triumphant Democracy (1886) and Gospel of Wealth(1889). In that last book he stated that only philantropy could make life worthwile.