It was ALL about slavery, farming and their economic strength.... Worries about losing it, with slavery gone.... So they didn't want to give it all up, without a fight.
From what I can tell via all the research on my family roots, most didn't even know it was wrong.... I know that sounds strange to us now.... But to many every day folk, farming their own farms with their own 10 kids and maybe another farm laborer hand or two, never had or even saw a slave.
It was the rich plantation owners with politicians in high places who deceivingly pushed the fight on to everyone else who had nothing to gain by slavery, under the guise of state's rights.... Imo.
I have relatives that were the rich plantation owners and relatives that were just family farmers, with no slaves at all.
I have relatives that freed slaves upon their deaths and relatives who left their favorite slaves their cabin and surrounding land, enough for the freed slave to provide for themselves and their family...
And relatives who left the slaves they owned to another life of slavery, with their kids owning them now.
I have relatives who passed down their slaves to children in their wills, that gave instructions NOT to split the slave family unit apart when dividing up the slaves for each child.
But most of my lines of my ancestry living in Alabama, Georgia, North Carolina and then Texas had no slaves,
But still fought as Confederate Soldiers.... There really was not a choice....they had to sign up between certain ages... Something like 16 to 50. before the war started.