I think it can be a mistake when the left just vilifies the 1% income bracket. In the culture wars, part of the 1% tends to lean left.
Income disparity is a big problem, but I think it goes beyond just the 1%. Ideally, we should strengthen the progressive aspects of our income tax system. That means higher income people should pay more including 1% paying the most. With a more progressive tax system, other higher income people would pay more as well. The 1% would be at the top so they would pay the most, but other upper income people would, most likely, pay more also.
Income discrepancy also means that upper middle class has gotten way ahead of most of the rest of society. Possibly the top 20% needs to pay more, but I don't have a definite figure. The goal wouldn't be to draw a line around a certain group of folks just to vilify them. It would be to have a more progressive tax system. Upper income people could still be a welcome part of our communities.
Taxes do generate revenue for government, but another effect could be to tame some of the inflationary forces in, for instance real estate, where prices can go way out of line with other things in the economy. Housing prices can go up around 10% per year while the overall inflation rate, including most wages, is around 2%, for instance. I'm not citing exact numbers, but more the concept.
The income of upper middle class is a big part of what drives the lack of affordable housing for lower income people; including what could be called most of the working class. Upper middle class has created an inflated market for housing as home values skyrocket in many locations. Other things like the high fees charged by many professionals, such as doctors, drives a lot of the problems with access to healthcare and so forth.
If I were to redo the tax code, I would make the graduated tax steeper, as it was before the so called Regan Revolution. I would also provide some relief for business. If wealthy and upper middle class wish to invest their money in job creating business, there could be deductions. One doesn't want to smother business with taxes. On the other hand, if the money is just kept as personal income and used to drive up already existing investments such as real estate, I would increase the tax on that. It wouldn't have to be too punitive, but migrating more toward a progressive tax system could help bring some balance back to our economy. A healthier and more balanced economy could bring benefit to all.