Maybe if you only count intelligent enemies. Otherwise asteroids, gamma ray bursts and planetary dynamics are also dangerous. A second planet would let us recov

Maybe if you only count intelligent enemies. Otherwise asteroids, gamma ray bursts and planetary dynamics are also dangerous. A second planet would let us recover from all of those. Except for maybe a gamma ray burst depending on how close the second planet was. Even if you limit the scope to ways we may kill ourselves: Nuclear war would likely be contained to a single planet. A second would at least improve our odds. Disclaimer: I very much agree with the sentiment of the comment you responded to. I don't even plan on having kids or anything. I just imagine a dark and boring universe deprived of humanity drifting off towards it's icy death with nothing to replace us.