It wasn't worth it.
Slavery would have died out on it's own.
That was the belief at the time of the Revolution -- that slavery was a dying institution. But economic forces and developments had brought about a resurgence of slavery, thus leading to the conflict.
Putting up with slavery for even one day in the United States is what was not worth it.
Slavery is still practiced in some parts of the world. If half of the United States had continued to embrace it by becoming a confederacy, there is no telling where we would be today in terms of slavery's acceptance in the civilized world. It is also likely that the North would have been economically ruined and then taken over by the South, and slavery may have continued to this day.