Trickle down doesn’t work, it has never worked. If you think of the American economy as a ship. The poor are the remains of other ships, of all the history of sunken ships and garbage on the sea floor, they get simply left behind, they are of no importance to the economy, you can’t see them from the surface of the ocean.
The middle class are the hull, just like in this cartoon, the hull of the economy is being filled with water, its bolts are coming undone. The shrinking middle class is joining the poor in America. And soon they will be merely another wreckage on the bottom of the ocean.
And what of the rich? The superstructures on top of the ship? They may float for awhile on top of the ocean, but without a hull, they will either sink with the entire US economy, or will simply move on to other economies of other countries. If the poor and middle class lose all purchasing power, if they are unable to buy things, then there will be nothing to keep the rich, and the economy as a whole, afloat.