And, one can argue from fact, slavery in the US wouldn't have lasted as long as it did if owners of fabric mills in England hadn't profited from it. Because of recent historical studies in England and the US it's been found that Mancusian and other mill owners in England had stockpiled enough US cotton to last four or five years. Cut off the supply lines, as the US blockade did, but send the CSA (and yes, the North as well) guns enough to keep the Late Unpleasantness going as long as possible -- then artificially increase the cost of cotton cloth and attribute it to the "shortage caused by the war."

Don't doubt me on this -- my wife (who has a BA in math, an MA in Library Science, and a JD) and her friend Mary (BA, American History, ABD in American History, JD) have been researching this matter for literally years. And yes, throughout the War Between The States the North as received cotton from the South either as prizes auctioned off or through smuggling (get it over the Ohio River, put it on a train to the East, nobody asks questions).

As for "a rich man's war and a poor man's fight" I refer you to the desertion statistics of the South, especially toward the end of the War, in "The Life of Johnny Reb." (NB: the author was a very much acclaimed historian).

Greed was big factor (although not the only one) in the CW.