Are you suggesting we create a world government to ensure there's nowhere on Earth people can flee to to escape high taxes?
So what do you do when the rich leave for Mars? Chase them there to make sure you get your pound of flesh?
Is this really the kind of world we should strive to create?
>>You lower taxes, the rich suck money out of the local population until they get a better deal.
Maybe you're looking at it wrong. The rich aren't cows to be milked. The relationship between an individual and a jurisdiction should be mutually beneficial.
If the jurisdiction has something the wealthy individual wants, they will invest there.
If the jurisdiction is losing wealth as a result of the activity of the wealthy individual, then clearly there are negative externalities that it is not punishing with penalties, or subsidies that it is providing without a proportionate benefit, that wealthy people are taking advantage of.
The solution there is to change the way government programs are structured to make business models that suck wealth out unviable.
If the programs that the taxes the rich pay for provide a greater benefit to the rich than the cost of the taxes, the rich will move/invest in that jurisdiction. The stable equilibrium is not zero taxes with no government.
As for growing income inequality, the solution is not forcibly redistributing income with a totalitarian world government that destroys/sanctions independent jurisdictions until they fall in line.
The solution is to find out what structural forces allow those with greater capital to accumulate wealth at a faster rate than those with less capital.
Perhaps the government is introducing structural barriers to full economic participation.
One example would be transaction taxes, like the sales tax. These advantage larger organizations that can avoid financial transactions by keeping their activity in-house, something smaller businesses can't do by virtue of being more specialized.
Another example would be securities laws, which necessitate use of highly paid professionals to get approval from the centralized regulatory gatekeeper to offer stock to the public.
It now costs $6 million to do an IPO, and many elite in the government and securities sector are looking to shut down unregulated cryptocurrency token sales that offer people who can't afford those sums a more affordable means of raising capital.
Maybe those concerned with wealth inequality are not concerned enough about these things, and are inadvertently contributing to the very centralization that is behind these problems by calling for more power to be given to centralized governing institutions in their pursuit of tax collection.
Something like 12 out of 20 of the wealthiest counties in the US are suburbs of Washington D.C. Maybe you're not looking in the right place for the source of the problem.