And David Koch has died. He was a billionaire businessman, one-time vice presidential nominee, and conservative mega-donor.John Yang looks at his life and legacy.David Koch helped his brother Charles expand the Wichita-based Koch Industries into one of the largest privately-held corporations in the world.He quickly became a notable figure in elite New York social circles.The business eventually became the fuel behind one of the highest-spending political action groups in modern American politics, Americans for Prosperity.Americans for Prosperity is responsible for the content of this advertising.The anti-tax, pro-small government group poured hundreds of millions of dollars into conservative candidates and causes,often through untraceable so-called dark money contributions.The president's doing a mediocre job. The oil-and gas-based Koch network spent just under $400 million on the 2012 election,an unparalleled sum at the time that filled the airwaves with attack ads.Obama's health care law is actually one of the largest tax increases in history.Targeting President Obama and the Affordable Care Act, while long denying climate change.I'm basically a libertarian. In a 2014 interview with ABC's Barbara Walters, Koch defended his political contributions.Do you think it's fair that just because you have billions of dollars, you can influence elections?