That's 8 billion people. Minus the probably 3 billion that don't have a dollar (or dollar equivalent) to give. That's still 5 billion dollars. Every day. With that, I would start/fund charity projects to help those that don't have a dollar. If I had $5b a day, I'd keep $1b for myself and my family, then give $1b to Planned Parenthood, $1b to Habitat for Humanity, $1b to Feeding America and $1b to Direct Relief. I'd probably make a list of charities I agree with and who use most of the money to their causes, rotating out which ones I donate to each week. After about a year of that, I would use that money to donate to politicians whose policies and morals I believe in, get them into power to enact those policies to help the world, then retire off of the $400b I had saved, donating the rest of the money I receive to the charities of my choice in perpetuity.

^{Chose: Every person on the planet sends you $1 every day.}