It’s a lot easier to influence life around you when you have billions. Think Gates or Zuckerberg. They use their money for good causes and it generally makes the world better, and creates thousands of jobs.
PG is a billionaire too now, but you don’t see him buying yachts. Instead, he lives in a modest home and drives an old car. Meanwhile, he’s been getting involved in social causes like healthcare, wrongful-imprisonment, and so forth. That’s a noble way to spend billions.
Of course, only a few people would become billionaires, but even so, you don’t have to be a city planner to fix cities. You can do it with software (http://getremix.com — a YC company).