Not at all. In fact, IMO "ST" generally ignores how expensive planets are. There's an enormous delta-vee cost from planet surface to orbit &/or back, & it has to be paid somehow. So any spacefaring species is much more likely to build permanent habitats than planetary colonies (except for research). I'd expect asteroids or small, uninhabited moons would be far preferred. For individuals, sure. For society at large, that falls inside the range of variability. For society to select for savagery, there have to be broader cultural reasons, reasons "us" should fight & kill "them". The first, & still best, reason is, "them" wants to steal our stuff: from that, walls, armies, & war. Not genetics, tho: culture. It will be dramatically reduced as soon as somebody figures out a way to make money on it. "[E]asy, safe and available for about all" will be a distant second, just as it was for steamships. It took almost 500yr for transatlantic travel to become common, & about 70 before steamers made it profitable (thanks to the Royal Mail subsidy to Cunard with Royal William); within another 25, people were coming across in steerage by the millions & the profits were huge. Then somebody figured out how to do it with airplanes...&, yet again, they needed a mail subsidy to start with. When somebody figures out how to get a government subsidy for space travel, or how to tap an asteroid for profit (which is much easier), the same is likely to happen. Entirely true. However, consider the U.S.: more space for radicals & rebels, & more wealth than for any society in human history. The first O'Neill hab, with the first powersats, will make the U.S. look like Bangladesh: crowded, restricted, & poor. I hesitate to argue with Larry on this one, but I disagree. It's one thing to choose pacifism; it's another to avoid self-destruction, & learn to avoid needless conflicts. And space is big... Plus, the delta-vee costs of planets make invasion pretty stupid, even allowing for the vanishingly small chance any alien will find another species' homeworld an attractive environment. Can you imagine Man invading Venus? (BTW, the "invaders from Mars" makes about as little sense.) The "ST" conceit of "Class M world" is just that: a conceit, a convenient device. It has no basis in reality.