What is "enough" depends on the person, both on his need and his mind. Some people make more than enough for what's needed for their lifestyle and still "It's not enough". Ever wondered why some company top brass still engage in illegal schemes to make money even though they're already fuckin rich?
The quest for money really depends on what every individual sees as their priorities. Some people like to live an expensive and flamboyant lifestyle. They want the best houses, cars, clothing, and holiday location regardless of the cost. Such a lifestyle gives them fulfillment, hence they are willing to do anything to afford this type of lifestyle.
If I can provide for my family's basic needs and contribute my own quota to the development of my community, then I am content with what I have. My greatest achievement wouldn't be how much I have earned but how many lives I have touched positively and how happy I lived. And my greatest joy, for now, comes from spending time with my family and watching my children grow.
It is also quite interesting to see many billionaires giving out a large part of their wealth to charity.