The estimated that between $2 and $4 billion worth of slave property was in the slave states.
Split the difference and call it $3 billion. We are to believe that protecting this property was the sole motivation for the southern states, whether the southerner opting to leave the Union owned a single slave or not, they all wanted solely to protect slave property.
The northern states, by a couple of estimates (by Yancey and T. P. Kettel, a northern man) was that the United States gained $250 million in income per year from having the southern states in the Union, but northerners were unconcerned about something as tawdry as money. They only wanted to free the slaves. (Of course, nobody in the north wanted to spend their own money to buy the freedom of the slaves. They wanted someone else to bear the cost of freeing the slaves. And nobody in the north wanted the freedmen to move to their states. No, no, those freed slaves had to stay where they were. We don't want them here in the north. And while somebody should provide the freedmen some land to farm and some implements to farm with, nobody in the north wanted to spend their money to achieve these indispensable ends.)
Anyway, in 12 years, if peaceful secession had been allowed, what was left of the United States would have lost an equivalent amount of money in income ($3 billion) as the southern states would have lost in the event of immediate uncompensated emancipation. Yet, somehow, southerners were motivated only by money, and northerners were above all of that. I guess they were just "better people."