We worked very hard for what we have. And you?
Obviously, this isn't true for everyone, and it is also the case that some uber wealthy didn't work all that hard for their wealth. They may have worked hard and diligently and smartly initially and now expand their wealth as whatever company the own grows in value.
I think the problem is with the core assumption that "working hard" should be a necessary component to "gaining wealth". It shouldn't, in my view. Plenty of folks work hard and struggle financially, and others work rather little and do very well. If you think that's unfair, OK, it may be, but one can imagine government policies to "correct" that unfairness that could have negative unintended consequences.
Our INCOME tax system is more progressive than most of the ones in Europe. Folks don't appreciate this here. Countries like Sweden have to tax middle income levels sharply, in addition to VATs and other taxes. And yes Sweden has more billionaires per capita than does the US.
If you really want to correct the above unfairness, it behooves one to check what other countries have tried, and how that has fared.
I would like substantive changes to our income tax system personally, but I'll leave it at that.