Yes, that wouldn't be ethical. It's not a question of paying more than others, it's a question of taking more for yourself personally than the value of the work you personally do.
Let's skip the consulting firm thing because that sort of business has a lot of ethical questions inherently, and just say they became a billionaire selling widgets. Let's also posit that widgets are a useful, quality product that enhances the lives of those who purchase them in some way. And we'll stick with your proposition that they pay $200 an hour to their employees.
If they became a billionaire, it is still unethical. It means two things: their employees wages should have been even higher, and/or their product should have been less expensive. It'd have to be more than a vague hypothetical to pinpoint where the most unethical stuff is happening, but it IS happening, because a human is not capable of doing work worth a billion dollars in their lifetime.
Inheriting a billion or more is not inherently unethical because you didn't necessarily have a hand in accumulating it. However, few people will remain ethical after that, because it is difficult to possess that level of wealth without some of it being used unethically. Perhaps if you converted it all to cash and put it in a money bin, Scrooge McDuck style, you could know that your wealth isn't out there doing unethical things, but there's few other ways.
People fighting AI are fighting to keep this broken system. AI has the potential to, over the course of this coming century, eliminate all human labor.
Our objective shouldn't be to fight that, but to ensure that as it happens, humans are taken care of and the benefits of this propagate to us all, because those who are trying to hoard the benefits to themselves are happy to see people fighting to 'limit' the use of AI or to 'save jobs' because it means those people are not fighting them.