I'm not entirely unironic in this position, but largely so. In theory, the richest person in America (or other tax jurisdiction of your choice) should be left with NOTHING. If their income is even faintly representative of their contributions to society, they would have nothing to worry about, as people would value their contributions and would shower them with gifts, probably millions of dollars worth in the aggregate.

Some advocates of progressive taxation point out that top US income tax bracket was something like 90% in the Eisenhower era, although in practice almost everyone in that tax bracket exploited various loopholes. I could see 0.9 times percentile ranking for all incomes above the "poverty line." The 99.99th percentile would still have millions after tax. That would admittedly be somewhat hard on the mere 1%, as the 99th percentile itself is basically the doctor/lawyer tier.

Most likely a tax-the-rich schema would include income or wealth taxes (ideally both) that only apply to people well above even upper middle class. That being said, I think the professional-managerial elites need some education in how wide the chasm between them and the median (let alone the precariat) has become. University educated people in general are my allies on social issues, so I'm not looking to soak them, but a little propaganda oriented toward UMC liberal guilt might be salutary.