Aliens! So they're going to do interstellar travel, but they're not going to colonize or build space habitats and solar collectors? That, right there, is silly. But here are reasons: — RogueAI
You have no idea if they would be inclined to build those things nor can you have any idea whether they would need to build those things. Those things you mentioned are the kinds of things humans might need to build, but an alien world could have elements and propulsion systems that we do not, they could be evolved to travel through space For all you know and need none if that. This sense you have of what an alien species would build or leave for us to see is based off of anthropomorphised fiction. No offence, but you seem to lack the imagination for the endless possibilities that explain why those things (megastructures and such) might not be present.
1. You don't put all your eggs in one basket. Existential threats exist.
2. You don't leave energy lying around if you can cheaply collect and store it (this goes back to the implication that if interstellar travel is possible, efficient antimatter production and storage is possible). Spare energy is never a bad thing to have.
3. You maximize available computing power.
4. Population pressures (possibly mitigated by population controls)
5. Convenience (there are benefits to space habitats) — RogueAI
1. So? That doesnt mean we would see these megastuctures, you dont even know If they keep the eggs in baskets. They could easily have other ways of dealing with existential threats, and have existential threats humans are totally unfamiliar with. They can just as easily have existential threats we do not, and us with ones they do not.
2. This is nonsense, there could be any number of reasons to leave energy lying around. Humans do it all the time. Again, you lack imagination here. We leave sources of energy lying around because we have better sources of energy, and better technology to utilise the better energy sources. It could easily Be the case we are unable to detect their sources of energy, or any of thier mega structures. (Maybe they dont want to be found)
3. Nonsense again, you MIGHT maximise available computing power but you might not. Again, humans all over the earth show us that this just isnt true. Even if we did, why would we expect aliens, especially more advanced aliens, to maximise it? Do they even have computers? You have no idea, you just assume they do because we do.
4. You are assuming they have population pressures. They easily could not due to a different evolution process, different culture/laws or technology so complex we dint even recognise it. Youre just guessing.
5. How do you know it would be convenient for them? How do you know what benefits this alien species or doesnt?
You said you would present reasons, but you didnt provide any reasons at all. You listed possibilities, and you listed blind guesses.