Niceness does not encourage people, if through hard work a person can lead a nice life then that is the biggest encourager. Progress in life requires hard work, so a person born in a rich family cannot become rich. Because he needs hard work, only hard work leads to the top of success.
Hard work or getting away with crimes or taking advantage of the system before someone else does it. There is a saying in the popular culture here in this part of the world: "Behind a huge fortune lies a huge crime", which I admit it is rather a cynical way to approach the success of others, but it certainly applies in many cases.
Even to this day, there are huge companies in developed countries, like the United States and even Germany which continuously have their teams of lawyers close to them, since they always try to find legal grey areas to screw the common people over, for the sake of money.
You should investigate a little bit of the shady practices of bank of America, for example, how they try to over-charge their clients for no reason and hopefully not to get caught red-handed by the government.
So, while there are indeed people who built their fortune through hard work and good investments, there are others who abused the system to collectively steal and got away with it.