Likewise, a warlike race of aliens is not hard to imagine. Wars are "expensive" in that they cost lots of money, but when america wages war the money that is spent in such great amounts is spent on American troops and government contractors, who in turn take the money they earned and spend it on other goods, so it does not "destroy" the money. In fact, war is generally an economy booster. As far as the destruction of resources, assume this hypothetical alien race is warlike toward OTHER species, not internally. The things they are destroying, then, are not on their homeworld, but on the worlds of those they conquer, and every world they conquer is another batch of resources for them to sap before moving on.
I just think you can't really predict the way another race would develop based on a random sample of 1 (humans).
Dude, broken window fallacy: http://en.wikipedia.org/wiki/Parable_of_the_broken_window"
Knowledge is created by a process of replication (with errors), and selection. In human-level terms, truth seeking requires being open to new ideas, including criticism, and replacing faulty ideas. Attitudes like, "some things should remain mysteries and aren't for us to know," "I can believe whatever I want as long as it makes me happy," or whatever it is behind superstitions, prevent knowledge creation. If those attitudes are too prevalent, and applied to too many subjects, you can't develop space flight, and other advanced knowledge.
You have it backwards. Wars create wealth. That is, in part, why we keep having them.
Also, some wealth is lost in the form of bullets, bombs, and other weapons that are used in the process. It's not the total cost of the bomb, but it is the cost of the physical material that makes the bomb.
Physical goods are destroyed. Man hours are used up. How is that wealth creation?
More controversially, war deaths reduce the supply of labor, making it more valuable for those who survive. The Black Plague had a similar effect.
But you could have researched that anyway, without breaking the window first. When you are forced to research something b/c of a broken window, or war, you set aside what would have otherwise been a higher priority.
Being forced to do something is not a good way to discover the best priority. Free choice, while imperfect, works better.
One of the most famous explanations for our need of physical destruction of goods was given in "1984"
Wars are very expensive and destructive. It's hard to become advanced when you keep destroying wealth. On Earth, as we've become more peaceful, we've also become more wealthy, and more able to travel space. The same logic for why this would be so on Earth, applies elsewhere.