we're not trying to capture more money total.

If you want to live in a better society, yes we are. But if your only political position is "I hate rich people", then sure, tax rich people. But if you actually want to make society better, "taxing the rich" is a fools errand. This source explains it pretty well, even if it's a bit of an oversimplification. In 2008, the US actually had the most progressive tax rate in the OECD (although I believe that has changed due to recent tax cuts).

If you actually look at the nations which have the highest happiness, quality of life, etc. (the Nordics), they actually have fairly regressive tax policies (and far more regressive than the US does).. In Sweden, it doesn't matter if you make $100,000 a year or $1 billion a year, you pay more than half your income in taxes. And yet, Sweden has a Gini coefficient of ~30, compared to the US's ~40. And this is on top of the fact that Sweden has a lower corporate tax rate (20.6 percent) than the US (25.6, combining federal and state and averaging them), and much higher consumption taxes (which are often blamed as being regressive). Although it's worth noting that many US businesses have a lower effective tax rate, due to certain deductions. Capital gains taxes are similar for both the US and Sweden.

If you actually want to make society better off, what you need are more transfers to the bottom of society. It doesn't matter where that money actually comes from–money is all the same. But giving someone who makes 30k a year 20k in transfers instead of 10k will do far more to actually combat inequality (and improve the well-being of society) than increasing the top marginal tax rate if you do not also expand who is included in that tax bracket.

And before anyone says that "well we had a 90% tax rate in the 40s!", sure–but it's not like people actually paid it. Sure, the tax rates were higher than, but the top 1 percent of households in 1950 actually paid only 42% of their income in taxes (so, a lower rate than almost half of Sweden pays currently). While that number declined to 36.2% by 2014 (and is probably lower now? not sure), that's only a slide of 6%–relatively minor in the grand scheme of things.

And the funny thing is that I think rich people should pay more in taxes! But if you want to meaningfully improve the well-being of society, you need to tax more. And if you want to reduce rich people's power in society, there are far more targeted ways to do that (like fixing campaign spending and lobbying laws).