I readily admit this. But you would also then have to admit that those cities contain some of the wealthiest Americans who pay most of the taxes.
Northern cities, like Boston, Chicago, and New York, do indeed contain some of the wealthiest individuals. But many rich people live in the country rather than in cities, and many live throughout the South. You may be unfamiliar with the staggering amount of money available around Richmond, McLean, Middleburg, and Charlottesville VA, around Atlanta, Charleston, Miami, Dallas, Houston, Fort Worth, and in enclaves and on country properties everywhere in the South.
I really do not quite take your point. Are you suggesting that there would be some sort of economic disadvantage to the South to leave the Union? Surely not. A group of states organized around principles of capitalism, instead of socialism, would be at a great political and financial advantage. Besides, if we had a nation with only a small part of the exchequer spent on welfare and social programs, not only would they prosper but the indolent would then make tracks for the generous Northern cities. So we would be free of the need to support so many of them. Enjoy!