A major point of Ray Bradbury's "The Martian Chronicles" seems to be that use of technology must be thought out very carefully, not rushed in to. "The rocket made climates," but that technology which could change the world couldn't change the people of the world, that responsibility lies with themselves. In Bradbury's stories, humans spread to Mars to avoid an imminent war on Earth, killed the native Martians purposefully or accidentally by disease, and then went back to Earth when war broke out, leaving both worlds barren.
According to one man, anyone with any sense wanted to get away from Earth because "there was going to be a big atomic war," an out-of-control technology. But men like this had no plans, no ideas of how to colonize Mars, they just had the technology. From a lack of precautions on the part of the humans, most of the Martians were killed by chicken pox, making way for more Men. One of the men from the fourth expedition set up a hot dog stand, expecting thousands of people to flee from Earth. When a Martian came by the stand, the man shot him because he didn't know what the Martian wanted and was afraid of the technology he might have. But with war breaking out on Earth, everyone abandoned Mars to help their native land. Then, because of the tremendous technology that it had developed, civilization on Earth destroyed itself, having already destroyed Mars' civilization.
Bradbury seems to be showing that technology must be thought out carefully by giving counterexamples, albeit fictionally. People developed powerful rockets and then they used them to rush headlong away from Earth to avoid war, killing the Martians in the process. Then they rushed headlong back to fight the war with terrible weapons, killing themselves. Humans' foolishness and haste to use technology without understanding left no winners and few survivors.