Leaves out the argument that interstellar travel is <i>hard</i>, that is, the distance between the stars is the filter.<p>If you think interstellar civilizations are based around stars and inner solar system planets it is very hard. Some lucky civilization might pull it off once (say they had an 0.5 ly hop) but doing it again and again and again is a different thing.<p>It's hard enough to do that "people" might not care. Self-reproducing VN probes wouldn't bear fruit in my lifetime or my children's lifetime so why would I care?<p>The most plausible route for interstellar travel I think is developing a D-D fusion economy that can live off comets and other interstellar bodies and "people" who had that might decide that inner solar system planets and stars are a big waste of time. If "grabby aliens" came to our solar system they might steal Pluto or Ceres but certainly not come to L.A. (or even Detroit) to steal our water as they do in<p><a href="https://www.imdb.com/title/tt1217613/" rel="nofollow">https://www.imdb.com/title/tt1217613/</a><p>Megastructures much larger than<p><a href="https://arxiv.org/pdf/2011.07487.pdf" rel="nofollow">https://arxiv.org/pdf/2011.07487.pdf</a><p>are not plausible (where do you get the stuff?) and not motivated.