I don’t necessarily have a problem with a person having a billion dollars. I do have a problem with the influence of money in the U.S. political system. Moving to federally and state funded election would be a start. That and a tax on wealth, not income, that would erode the accumulated assets over a generation would lead to greater equality.
There are basically 2 ways to make money. You can provide value where people are willing to voluntarily trade their own labor for that perceived value, and taking it by force. Bill Gates is an example of both. His contribution and a lot of the money he earned was because the value of his product was worth far more to people than the asking price. He received a fraction of the value he created in the world. He also got the government to give him a monopoly on the ideas that were implemented, preventing others from implementing those ideas with violence. I'm in the camp that says the latter is inexcusable in a society. I suspect gates and most billionaires would not be billionaires if it weren't for the monopoly protections enforced by government. Where would the rest of that wealth have gone? To anyone who was able to compete against the ideas.
I stopped reading at “Most wealth is created, maintained and sustained by extracting unearned rents from the rest of us” because that is a description of a zero-sum situation; it is impossible to <i>create</i> wealth that way, one can only redistribute it. Bill Gates for example created a company that was valued by the market at many billions of dollars, billions of dollars of value that did not exist prior to Microsoft. He did not “trick me into paying more than necessary for something out of ignorance” (asymmetric information), but instead created a tool worth thousands of times its cost to me (a software developer).
Saying that there's something bad in 'rents' is a hypocrisy. Every income which is not a job, is rent. Profit from every business, economically, can be split into rent and (real and/or virtual) salary of the owner (with small business usually being wholly or mostly "salary"). You can tell there is some non-"salary" component when you can sell your business for the price higher than liquidation price of it's physical+financial assets. That price is a capitalized cost of the rent. There's nothing morally wrong with it.