2) Koch family (Net worth: $86 billion)

The Koch family is behind Koch Industries, the second largest private company (around $100 billion in sales) in the US. Charles and David, two of the four siblings have worked really hard to grow the business. These two rank among the country’s top 10 richest individuals. Today Wichita-based Koch Industries is a multinational corporation, with subsidiaries involved in manufacturing, trading and investments.