Actually it was just slightly more than half. 1.8 million slaves were involved in cotton production, which leaves 1.4 million who were not.
Cotton was the only thing making slavery profitable.
So all of those other 1.4 million slaves were a money-losing proposition? It makes one wonder why people kept buying them, at higher and higher prices, in the non-cotton producing areas.
Clearly you understand the connection between slavery and money. Since you went to the trouble of looking up some stats, perhaps you looked up what they did? Some grew tobacco, some grew indigo, and various other stuff, but I doubt tobacco or indigo would grow any better in the territories than the main crop of cotton.