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).