Got to be blunt - I rather disagree with this premise that evil isn’t pragmatic, or that either the CSA or Nazi Germany are inevitably going to collapse.
The South is the more straightforward one to address - during the war, Tredegar and other Southern factories experimented with slave labor and found it more cost-effective than free labor, once the upfront costs of purchasing the slaves was paid. It isn’t inconceivable that being deprived of cheaper manufactured goods from the US or Great Britain results in a South that industrializes off the backs of its slaves in even more hellish conditions than the plantation fields and stays afloat economically well into the 20th Century (at least provided that A. The slave population remains self-sustaining, which could be difficult if the U.S. freed too many slaves in Virginia and Tennessee before the war ended, and B. The CSA somehow survives as a political entity when it’s constituent states could constitutionally secede any time they wanted).
Germany on the other hand is both easier and harder: theoretically, if you properly distribute all the clothes and personal items you stole from the Holocaust victims, and gave people free land well-watered with the blood of its former owners, and expand your infrastructure properly on the backs of the corvee labor you enslaved half of Europe into, then, theoretically, the price of foodstuffs should go down (same/more supply, a lot less demand), the price of manufactured goods should go down (same supply/demand circumstances, plus most European raw materials being available tariff-free now), purchasing power should go up (stolen wealth) and so on. This requires the Nazis to not be as corrupt and incompetent as they were OTL, but as pretty much any Nazi Victory scenario has the base premise of “What if the Nazis were not as corrupt and incompetent as OTL” it might well be assumed that they could win the peace if they’re successful enough to win the war. Really it’s disturbingly easy to imagine a perfectly bucolic universe of pretty, blond German girls decked out in gold jewelry dancing unknowingly on the mass graves of millions, and I’m actually impressed that SpanishSpy captured that tonal horror so perfectly in his recent vignette. The only real long-term problem with this universe comes a few generations later as the free nations of the world rapidly technologically outpace an academia raised on fuhrerprincip.
But I think that focusing too heavily on the CSA and Nazi Germany distracts from the broader point, which is that ultimately, it is both intuitive and borne out by countless OTL examples that the best way to make your life/your people’s lives better, provided morality can be made a non-issue, is to kill someone else and steal their stuff. The logic of Raskolinov is the logic of Robespierre is the logic of Hitler is the logic of Caesar is the logic of Stalin is the logic of any robber/burglar/shoplifter you can think of. In a moral-less universe, it’s generally sound logic. Wanting the bad guys to look like a lousy place to live in order to easily differentiate them from the good guys just distracts from the reason why they’re bad to begin with.