Is PoS based directly on wealth? I'm not sure of how it works and would appreciate a link related to this.
The same thing happens in any capitalist society based on morality. (no forced distribution of wealth) Example: The Kennedys and the Vanderbuilts and the Rockefellers no longer have an amassed fortune. It has been spent by their heirs and distributed morally (not by force) to society.
The difference with cryptocurrencies is taxing the wealthy and charging a death tax is increasingly difficult to do which isn't a bad thing but combined with a wealth transfer protocol designed to primarily benefit the wealthy this presents a huge concern.
Sure, some of the initial bag holders will spend all there wealth on hookers, drugs or charity. Perhaps their children will live such an extravagant lifestyle they spend more than the interest made from fees. Some large bag holders would go broke and new ones would replace them. The point is the system will have a heavy bias towards rewarding the already wealthy based upon there circumstance and not necessarily on any risks or efforts they have made.
If Nxt took off and became as big as usd or the euro you would see a much greater amount of income disparity than you do with Bitcoin or even fiat.