Lifestyles of the uber rich and not very famous

I was just looking at the list of the world's richest individuals, and it dawned on me that the overwhelming majority are pretty much unknown here in the USA. Outside of Warren Buffett and Bill gates, the rest are from other countries, and truth be told, names not recognized by us.

Warren Buffett (US): $62bn
Carlos Slim (Mexico): $60bn
Bill Gates (US): $58bn
Lakshmi Mittal (India): $45bn
Mukesh Ambani (India): $43bn
Anil Ambani (India): $42bn
Ingvar Kamprad (Sweden): $31bn
KP Singh (India): $30bn
Oleg Deripaska (Russia): $28bn
Karl Albrecht (Germany): $27bn

But here is what I thought about: the plight of Africa and many other countries without pure water. I have read that it costs anywhere from $70 to $300 depending on who is giving the estimate. If each of these top super rich billionaires gave just $30,000,000 each, a pittance by their standards, almost like a dollar to you and me, a million wells could be drilled. If just one gave a billion dollars, over a quarter million wells could be drilled. The impact of fresh water is tremendous for a local area. It allows them to be self-sufficient. It frees up hours normally spent just attaining this staple of life that we take for granted being available right at our tap. It allows crops to grow, and for the people living there to be more healthy.
The billionaires have the ability to change the world for untold millions.

Addendum:

I was looking at the list, and I realized that 5 of the top ten are from countries that are considered to be extremely poor. It makes me wonder about how wealth is distributed, and why we, as Americans, feel so obligated to help others when their own countrymen don't seem to care.