Michael Bloomberg vs. Rob Walton

In 2018, Bloomberg pledged $1.8 billion to Johns Hopkins University, his undergraduate alma mater, adding $1.5 billion he had already given the school. As a teenager, Bloomberg worked at an electronics company in Cambridge, Massachusetts.

Rob Walton, who has a law degree from Columbia University, helped Walmart prepare for its IPO in 1970. His daughter Carrie Walton Penner sits on the board of the Walton Family Foundation, which his parents set up on Walmart's 25th anniversary in 1987.