If prosperity was in the South and the North was bankrupt then the South would have won the war, no?
Why do you assume such a simplistic thing that the richest always wins?
The South only had farm implements and such, the North was an industrial powerhouse able to manufacture millions of weapons, and had ALOT more people (for soldiers) than the South.
A great bit of history is made up of countries being attacked for their wealth. The prosperity claim is a bit dubious nevertheless. The claim is true if and only if you count the squalid factory and mine workers of the North, but do not count the slaves of the South. But Slaves did have money, did make economic decisions, and were economic actors, not just production factors.
The TAX REVENUES were in the South. The South exported cotton and imported manufactured goods (a market the North coveted). From the customs on this traffic as much as 65% of Federal revenues derived.
The South proposed a 10% tariff on incoming goods. The North saw grass growing in the streets of New York and Boston.
This, more than anything, caused the War Between the States.