It took that long to dream it all up.
This actually makes a certain amount of sense. From what I have read, even without the war there was a growing dislike of slavery even in the south, and the slave owners were definitely a minority. Maybe they saw this seccession as the only way to preserve their “heritage”. They would control their politics much more if they didn’t have their counterparts (rich businessmen in manufacturing) in the north diluting their position on slavery.
Just thinking out loud.