Those on the low end of society might view the reason for the Civil War because of slavery, but those more globally minded, like the Koches or Soros of their day, look upon things differently.
To them, we are nothing but chess pieces to be moved about as they see fit. By flooding the Southern market with 4 million ex-slaves, and later cheap Asian labour, the industrialists get to keep their industries stocked with cheap labour forever. This means extra profits for them, regardless of what extra costs a free people might temporarily entail.
But their forever is now coming to an end.