If human societies ran according to the principles of Darwinian evolution, they would be evil -- or at least, would be prone to domination by people who are most capable of getting away with the sorts of things we consider to be evil.
We have moral strictures against such activity, though, and people tend to restrain their actions as a result.
Like any other economic system, capitalism is actually just a subset of human social interaction. So the same principles apply.
Societies that can adapt to change will thrive. Those that cannot stagnate and die out. There is nothing inherently evil about this.