Citizens should own the state and its assets, rather than the state own the humans like chattels. As with any legal property, the owners should be able to sell their property for what the market will bear.
2000 years ago, the Roman state crucified somebody who thought it an excellent idea to enjoy life on an individual, self-deterministic, free-will basis of voluntary consent among freely interacting people around the world. The state in the form of the Roman Empire did not take kindly to that sort of idea. The empire saw people as chattel property to be disposed of by the state as the powers that be saw fit, be it as slaves, lion fodder, serfs, artisans, minor functionaries, major functionaries, up to the emperor, with the power flowing from the top.
Many Jews were captured and taken as slaves to Rome. Christians, another form of Jew at the time, did not fare well either.
The harsh biological reality of the red in tooth and claw competitive, territorial, genocidal, tribal, alpha male, hunter-gatherer, found-wealth, biological world of mammalian social hierarchy, with the biggest, most powerful tribes winning more territory and females, was just how things were.
As many aspects of life have changed, the whole basis of such life has been reduced to near-irrelevance though gangs and criminals continue such atavistic impulses among modern citizenry and even some states continue to operate in the old way with places like Rwanda being hideous examples of raw tribal power.
But we still foolishly persist with the idea of citizens as state chattels.
We can own shares in huge collectively owned companies, we can own land and buildings in fee simple, selling them as we like and moving on. But we can't own the most valuable asset which is our share in the state and its properties.
If we move to another country, we lose all of our property despite generations of ancestors having worked lifetimes to produce an inheritance for their descendants. A fresh off the boat refugee from a Hell-hole inherits the lot on stepping ashore, being given a vote equal to those who produced the wealth over generations.
The current incentives are all wrong. The current system means people struggle to get near the levers of power to self-deal in tax revenue and property, and to reward people who reward them with votes. While the democratic system does avoid the worst of the megalomaniac Saddam style of government, it still leaves the political system subject to the self-dealing abuse of power.
For example the now-convicted previous immigration manager was ensuring her family and friends went to the front of the crowd trying to get into the free-loading society where the wealth of generations is being carved up. She was not ensuring the best for New Zealand. Taito Phillip Field conducted similar operations.
The incentives are now for the productive to flee to Australia and further afield, while the indigent, grasping, dishonest, and bludging crowd in to get while the getting is good. Those who flee can take only their personal assets.
With tradable citizenship, people would vote for the politicians who would enhance their personal value. Citizenships would be going up in value and price, not down as we have seen for a generation since NZ was 2nd or 3rd in the world in wealth and quality of life. Now NZ is down with Hong Kong, Singapore and many countries having soared enormously by comparison. NZ now rates like eastern European ex-communist places which were previously horribly poor.
Instead of having immigrants win a lottery, or having to, or pretending to, "invest" in NZ, we would have outright sales of citizenships to the highest bidders. NZ Inc. would sell Tradable Citizenships at the rate of perhaps 10,000 per year. They would be worth about $2 million each. That would provide revenue of $20 billion per year.
The buyers would make big profits if they decided to sell a few years later because the country would go from the back of the pack to the front as the whole economic foundation made a paradigm shift from a kleptocratic state to one run for the people by the people with individual people getting the reward for success rather than people in government circles taking the profits of control for their own purposes, ideology, and enjoyment.
With only 10,000 per year, it would take 100 years for another million citizens to be added to the population. That might not be enough to replace the existing population if the birth rate was to fall as it has done in Japan and Italy and other countries. New Zealand could take 50,000 such people a year and not have a crowding problem.
10,000 would mean a vast economic boom. It would be a simply spectacular shift, likely to be copied by other countries when their citizens see the advantage of people being owners of their countries rather than mere chattels to be disposed of at the will of their governments, unless they leave, abandoning their share of national assets.
Suppose somebody from Japan, China, USA, Brazil, or Hong Kong would like to live in New Zealand, at least for a good part of the time. They would not have to go through all the competitive bureaucratic nonsense of the current system. They could simply buy a new citizenship from the government, or an existing one, on the open market, and move in, staying as long as they like. If they decide after a few years that they no longer want to own a NZ citizenship, they could simply sell it on the open market and leave. They would keep any profit.
You can be sure they would be voting in the meantime for politicians who make good decisions which enhance citizenship value rather than cause waste, dissolution, social carnage, and New Zealanders to leave.
If a New Zealander decides to leave NZ to live in Australia, India or some other country, they could sell their New Zealand citizenship, rather than simply abandon all their and their ancestors' wealth-creating efforts. Suppose somebody marries an American and they go to live in the USA. At present, they simply leave and bad luck for them. With a tradable citizenship, they would have $2 million to buy another citizenship if required and to fund setting up their new life.
There could be a brisk trade in marriages, new citizenships, and changes in "allegiance" while people figure out how to best manage their lives.
New Zealand would go from has-been, sliding down the economic ladder with social carnage gathering pace, to top of the charts, most desired location on Earth, far better than Switzerland of the South Pacific, within a decade.