I think it is fair to say that it does not harm those who have a way to live a simple but secure and dignified life if someone else is able to live in splendor.
It is also fair to say that it does not harm the super rich to tax them at 45% of their income. They will still be living a very comfortable life, secure and dignified.
Wealth disparity is not an injustice unless someone is suffering in an intolerable living situation.
It may not be an injustice, but is it desirable for a society to promote a system that makes for extreme income disparity? And who gets to decide if their living situation is intolerable? Can we ask them? Or can we just decide for them based on what we think and what we know of their lives?
Feeling jealous that someone has more material wealth than you do when you have enough is not the same as suffering an injustice.
And being taxed at 45% is not necessarily suffering an injustice either.
For instance, if the “poor” in this country were all food-secure, warm, had access to medical care and had a standard of living that others doing manual labor elsewhere in the world would find enviable, it wouldn’t necessarily be an injustice if some other people in this country made many times more than the poorest.
Is that how we want to judge our own country? As long as there is some place on earth where people are worse off than our poor, we’re good. Nothing to worry about.