No argument there. I know of no one who believes that the CSA would (could?) defeat and occupy the entire north - or had any interest in doing so. But jeff davis certainly wanted his mortal enemy (the United States government) defeated. He knew that in violently breaking away from the commitment and the compact, he had set himself and his would-be confederacy as existential enemies and competitors. There could never be peace between them.
And REL made two attempts at realizing this goal, once in 1862 and again in 1863.
I believe the North and the South would have gotten along fine as two separate countries.