What did Andrew Carnegie do after he sold his company and he became what?

After selling his steel company to J.P. Morgan in 1901 for $480 million, Andrew Carnegie became one of the world's wealthiest individuals and a prominent philanthropist. He dedicated the remainder of his life to charitable endeavors, focusing on education, libraries, and peace initiatives. Carnegie established foundations and donated vast sums to create public libraries, universities, and cultural institutions, embodying his belief in the "Gospel of Wealth." His legacy includes the establishment of over 2,500 libraries worldwide and significant contributions to various educational and scientific causes.