You're repeating bullshit - The majority of spending in New Zealand is not by the wealthy but by the rest of the majority of kiwis[1].
If people earning less than $100k waste 5% of their income, and people earning more than $300k waste 50% of their income, then the people earning less than $100k are wasting more.
We're not in the USA with Jeff Bezos, so your point just makes no sense.
The majority of earners I know blow more than single digit percentages on unnecessary crap and luxury. For example my working class friends that spend more than 10% per week on booze and drugs - plenty of people spending more than $150 with a weekly income <$1500.
Look around you and there are obviously not a lot of superyacht stores. Plenty of booze shops doing a roaring trade and it isn't the $300k+ earners in them.
The wealthy people I know invest. If those investments are bringing foreign income into New Zealand, we already tax that and all New Zealanders win!
The government needs to get rid of the bad property investment incentives - those are where the wealthy are fucking over the non-wealthy. We have enough land and resources in New Zealand for everyone to have their own home.
Don't discourage people from investing in things that make New Zealand better off. Our taxation system discourages founding internationally competitive businesses, and it discourages owning more than $50k in overseas shares. And the majority of New Zealanders don't give a shit because the majority don't begin such businesses and they are ignorant about where their income to buy imports ultimately comes from.
Negative incentives matter, probably more than positive incentives. We all want to slowly tax the well off until they leave or until they are no longer well off.
[1] Data based on: https://www.ird.govt.nz/about-us/tax-statistics/revenue-refu...