The United States, excluding the antebellum southern states, was pretty much a free market economy up until around 1914 or so.

Of course it wasn't 100%, but it was a good approximation of one. Far from destroying the middle class, it created the middle class in America. Scores of millions of impoverished immigrants arrived on the shores, and moved up into the middle class.

The income tax on the rich came later.

I've heard it claimed that the middle class was created by the New Deal, but that is not very supportable. Just look at paintings and photographs of towns and cities from the previous century. Looks like middle class to me.

If you like, take a tour of the town of Gettysburg. It's been well preserved, with quite a lot of the same structures still there from the Civil War. They look like middle class homes to me. Have a visit and tell me what you think.