No. 6 -- George Kaiser, George Kaiser Family Foundation
NET WORTH: $9.4 billion
Buffett and Gates' fifth-richest donor, Kaiser -- who is No. 24 on the Forbes list of the Richest Americans, and worth between $9 billion and $10 billion -- is from Tulsa, Oklahoma, and expresses a philosophy in line with Warren Buffett's Midwestern wisdom.
Kaiser subscribes to the Warren Buffett view of dumb luck as the trigger for a moral calling among the wealthy to focus on charity, but he respectfully disagrees with Bill and Melinda Gates on the best way to spend the donated money. Kaiser is specifically focused on U.S. poverty, as opposed to the developing nation projects where dollar for dollar the largest charitable impact is possible.A key provision of the Buffett/Gates pledge is that the charities to be selected for donations are at the discretion of the individual making the pledge.