3 people who donated so much money they kicked themselves out of the billionaires club

Often when people think about money they think of having it, not giving most of it away. But for these three millionaires, who were once billionaires, giving is second nature.

With the help of Wealth-X, which does research and valuations on ultra-high-net worth people, we recently published a list of the 20 most generous people in the world. Wealth-X provided us with each philanthropist's amount of lifetime donations and net worth, as well as each person's "Generosity Index."

The Generosity Index shows the amount of money they have donated in relation to their net worth. Out of the 20 people, three donated more money than they currently have, making their generosity indexes greater than 100%.

In total, Jon Huntsman Sr., Suleiman bin Abdul Aziz Al Rajhi, and Charles Francis Feeney have collectively given $13.2 billion to causes around the world. The common conviction among them: True satisfaction comes from seeing your private wealth in the hearts and hands of the public.

Scroll on to see why these philanthropists are donating a majority of their fortunes: