As always, you miss the key point: those wealthy Northeastern Democrat merchants were political bed-fellows to wealthy Southern Democrat slavers and together they ruled in Washington from 1800 to 1861.
Then what happened?
Southern Democrats declared secession and Northern Democrats (especially New Yorkers) wanted to join them, wished them Godspeed.
As Democrats Northerners supported their Southern Democrat brethren, until, until... until... what?
Come on DiogenesLamp! You know the answer to this.
Northern Democrats supported their Southern Democrat brethren until Confederates began renouncing their debts, suspending their payments, stiffing their creditors.
And they did this even before starting war at Fort Sumter, so by the time of Fort Sumter even the most South-loving Democrats recognized the time had come to partner-up with Republicans.
But soon after 1865, Northern & Southern Democrats again wedded-up politically, thus ending Reconstruction in 1876 and electing their first post-war Democrat president (Cleveland) in 1884.
So, it was only during the Civil War that Wealthy Northeastern Democrats abandoned their previous allies and joined with Republicans to defeat them.
And today, those Northeasterners are still Democrats and still allied with Southern Democrats, who are now the descendants of the formers slaves Democrats oppressed.
And of course you know all that, but it just doesn't suit your anti-Republican narrative to confess that the worst of the loathsome Republicans were actually, well... they were Democrats, and still are!
Okay, so you get the concept. Now we just need to work on your understanding of who was going to lose economically with Southern Independence, and who was going to win economically with Southern Independence.
As I keep saying, follow the money.
Come on DiogenesLamp! You know the answer to this. Northern Democrats supported their Southern Democrat brethren until Confederates began renouncing their debts, suspending their payments, stiffing their creditors.
If you've mentioned this before, I must have missed it. What debts were being renounced? Which creditors got stiffed and for what?
And of course you know all that, but it just doesn't suit your anti-Republican narrative to confess that the worst of the loathsome Republicans were actually, well... they were Democrats, and still are!
I am not anti-Republican, I am anti North Eastern Liberal elite who want to shove their latest version of morality down our throats. It just so happens that in 1860, these people were Republicans.