Bill Gates and Warren Buffett made their fortunes in business (and continue to reap profits from their company and investments, respectively), and have spent years sharing their wealth with people in need through numerous philanthropic projects.
Now, they’re upping the ante, inviting the other people who run in their super-rich circles to increase their own commitments to spreading wealth. Specifically, Gates and Buffett want the super-wealthy to give away half of their net worth, whether during their lifetimes, or at the time of their deaths.