They do on the other hand hold a significant portion of the wealth. Unfortunately wealth tax is complicated, both because actually measuring the wealth for tax purposes can be hard, and the rich can (and will) just move away from any sufficiently effecient tax scheme.
So upper middle class ends up paying the bill.
The really bad part is that the middle/upper-middle class is the real cash cow, the top ~75%. These people are incredibly numerous and have good to incredibly good disposable income.
But since they are such a large cohort, you cannot form a policy around increasing the burden on them. And after all, the tech family pulling $450k/yr are still a "working grunts".
So it's all eye's on the top 1%, but a true wealth gap fix would actually come mostly from harvesting the wealth of the top 20-30%.
It's easy to tax certain assets, such as land. LVT is actually the ideal tax in many ways, since a LVT is undodgable. Actually it doesn't matter whose name is on the title.
Sufficiently high LVT will deter speculation, leading to collapse in land price and encouraging efficient usage of land and drastically affecting our political landscape.
> the rich can (and will) just move away from any sufficiently effecient tax scheme
England managed to confiscate the estates of its major lords through the inheritance tax.
The rich can leave, but they can't take their house with them.