Not everyone you meet in space may be friendly.
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A very rational assumption IMO. There seems to be an overwhelmin perception/assumption that advanced extraterrestial beings would be benign (for which there is no basis) .
If, hypothetically, an alien race has traveled here, they are likely thousands, if not millions of years advanced beyond us. We must be like an ant hill to them. Like human interactions with an ant hill, most would pass by without much notice. Some may want to study us for the sake of knowledge, others may want to study us to see how to best eliminate us. Others' first reaction may be to simply dump some gas on our mound and torch it.