Many other multi-billionaires in the US have signed the Giving Pledge [0], promising to give away more than half of their net worth to charity. Gates, Paul Allen, Warren Buffett, Carl Icahn, Mark Zuckerberg, Marc Benioff, Michael Bloomberg have all signed. Even Larry Ellison! But not (yet) Jeff Bezos, or for that matter Sergei Brin or Larry Page.

[0] https://givingpledge.org/