its because they want more and more, their never happy of what they have if they have 2 cars they'll want 5 if they have 5 cars they'll want 10. its in the mind of people that money is everything the price of happiness. celebrity's have so much money they could afford their own island but they end up being sad or depressed and kill themselves. for what? cuz they weren't happy and despite all the money they had. people want to make more money as to live a luxurious life to fulfill their goals in life (which is nothing wrong with that) cuz their not happy of what they have, im not saying its bad to make more money of course its ok but some people go to far with it even if they have everything they still want more. its like a saying stuck in their mind "the more money i have ; the better my life will be".