I envision a world where wealth is distributed in an equitable way, where people are paid fair amounts for their work and there's a limit to how much wealth a single person can have at a time. The incredible disparity that exists between the middle class and upper class doesn't sit right with me, those with exorbitant amounts of money automatically have ridiculous amounts of power that come so easily with it.
In order to curve this imbalance of money and power, taxing the ultra-rich larger amounts that are proportional to their wealth can mediate this inequity. Also regulating the "philanthropy" they take part in can help distribute the wealth evenly, so they don't use DAFs or self-owned charities as loopholes for tax evasion. There should also be some sort of regulation or law against billionaires being able to buy out large corporations and do whatever they want with them.