If I were the richest person in the world, I would provide clean water for any poor countries.  Clean water is important because we need water to survive.   Within 40 years we will barely have good, clean water.   Even now, poor people get diseases from drinking water from filthy rivers.  To help, I would collect great vats of salt water and the water would evaporate leaving clean water.   I would then guide the water to a giant freezer freezing the water.  I would then melt the frozen water and add iodine to get rid all of the miniscule contaminates.

Also, I would like to help the world by providing cheaper energy.  So, I would buy all the land in the Gobi desert for its oil reserves.  The Gobi desert has about 20 massive oil fields which I could use to make cheaper fuel.

The question is, how could I get all the power to do this?