Great analysis! It's so true that the wealthy play an important role in society, namely that of innovation and investment. Money is nothing more than a tool and so there is no injustice in placing those tools in the hands of those who are the most capable at wielding them. Especially when the use of those tools benefits us all.
The objection that wealth concentration hurts people is unfounded. The amount of wealth in the world is not a fixed sum and the accumulation of it is not a zero-sum game. It is based on productivity and productivity is highly expandable. This can be seen in just the last 30 years in which our global economy has made a few people richer than anyone could imagine. And at the same time millions upon millions of people in the developing world have been lifted out of poverty.
Or take a simple common sense example. The founders of the grocery chain Aldi's have made food more affordable to low-income people and it was that result in particular that allowed them to make their fortune. That is another important form of innovation: making products more accessible and affordable for people by creating more efficient distribution systems. These kinds of examples abound in the global economy.
There's an old quote that I love...
"Profit is proof that the capitalist has given something to society that it values more than the money it has handed over to the businessman."