My remark was referencing other civilizations in our or other galaxies. Who is to say that the concept of cost exists elsewhere if other civilizations exist?
Look at life on Earth, through the evolutionary process. There are several physical and behavioral manifestations in animals that on the surface seem exorbitantly high in cost. Huge elaborate antlers on some species of deer, lemmings swarming off cliffs, fish fighting (and dying) to get upstream only to spawn and die. But in reality, each can be explained as the price paid (in internal resources at least) for survival of the species and any one animal's protégée. The elaborate antlers on a stag, for example, allows in to win one-on-one battles with other males, thus allow it to be most likely to breed and have offspring. When lemmings breed too much, resources are taxed badly, and when a critical match is reached, they all stampede for better pastures (not looking for cliffs, but they're to stupid to know when one is coming up!). Salmon could simply breed in the ocean, but this makes it harder for their offspring to survive and prosper in the competitive ocean environment, so streams are a better place for it's offspring, even if it means the parent dies--the species is favored by this behavior.
Well, at some point the same will happen to us. We'll reach a point when resources get so scarce and costly on Earth that the ones in space will be a bargain. When that happens, we'll be in space, and as we continue to consume resources, we'll have to go further and further to get them.
Unless, of course, we make like the lemmings.