That argument is a bit circular. It is a bit like saying someone doesn't need to get a law degree until after they've opened a legal firm - there are some obvious cause-effect issues. If there is a tax on wealth, why would we expect there to be local examples of great wealth created that aren't physically extracted from the land? If a Norwegian had a great idea for a new product, presumably they wouldn't be stupid enough to hang around in Norway being taxed back into the middle class.

You can't presume that. They might quite enjoy living in Norway. More than they'd enjoy having twice the money, especially when both numbers are high enough to have anything they want.

Sure, but we are talking about democracy and power of majority. Majority of people may be better if there is no high wealth gaps. Future proofing of country economy is a related problem but it may be too far away.