Let's just stipulate that you are correct so that we can once and for all dispose of the notion that Lincoln's War was fought for some high moral humanitarian purpose like “freeing the slaves.”
But fight and kill Lincoln and his backers did for a purpose which was, for them, desperately important. And the reason: money.
Assuming, for the sake of argument, that you statement is correct is that worse than fighting to defend slavery?
Lincoln fought the war the Confederacy forced on him. Whether for money, as you claim, or to preserve the Union, which was the actual goal, the aggressor was Davis and the Confederacy. You question why Lincoln fought the war yet you don't ask why Davis began it in the first place. Why?