Should it ever become practical to do so, the reasons for doing so will look very similar to the reasons Europeans colonized America. The thing about densely populated environments is it requires lots of governance, and populations have a habit of increasing exponentially, which would be difficult for artificial environments to keep up with indefinitely. When you're on the frontier, you have a lot more freedom.

How so? You've already become adept at living in space, working in space, and building things in space out of materials you found in space or else it wouldn't be practical at all to travel to a new star system anyway. At that point, just build new space habitats.

It's an and, not an or. People get good at living in space. Some of them move next to a new planet because it has resources. Some of those people have to go to the planet to exploit those resources. The rest stay in space. Now you've got a populated planet. Maybe they'll do some terraforming. I'm not sure what will be practical, but it's not hard to imagine that at least some basic terraforming is probably feasible just by constructing life forms that can live on the planet and further move it in a direction intelligence likes, even ignoring massive, energy-intensive interventions.

Not all the space people have to move to the planet, just like when North America was populated it didn't depopulate where they came from.

Apart from what's already been mentioned...

Consider that the population of England during the colonization of America was around 3 million. Today, nearly 3 times that live in London alone. It's like asking why would anyone have bothered to risk traveling across the Atlantic for months to get to untamed wilderness when England could've just built more housing.

Adept maybe but that doesn't mean that living in space wouldn't involve compromises that people would rather not make / have to make on a nice big habitable planet.

Perhaps I'm wondering away from the initial proposal but think there would be some compromises that make life on a planet more desirable.

Unfortunately, we can't even build enough housing for humans on our current planet.

I think the reason earth-like exoplanets generate so much interest is not because of the terraforming / colonization potential but rather because they are more likely places where we might find alien life.

We have to wonder if they're thinking the same about us.

"That 3rd planet looks easy to colonize. I wonder if there are any upright, talking primates there?"

Totally agreed

Semi-related to this discussion is the novel _Seveneves_ by Neal Stephenson.

Essentially, the premise is that the Moon gets hit by a Very Large Thing, and humanity has to prepare for Earth being hit by some very large bit of the moon. Part of their planning is building a generation-spaceship, designed to last until Earth's hot atmosphere cools to a habitable level, so there is some discussion of "Why live on a spaceship when you can live on a planet?" However, it's not a deep focus.

The book has good reviews [1] and I'd strongly recommend it for those who like hard Sci-Fi. However, I would consider only reading the first two parts. The third part is rather extravagant and, imo, lost the thread of the first two parts. It certainly lost my interest.

[1]: https://www.goodreads.com/book/show/22816087-seveneves

You can step outside without being in a vacuum.

Have you read the Expanse books? They kind of touch on this subject.

Maybe they meant more of an O'Neill Cylinder, in which case you can step 'outside' onto the inner surface of the cylinder and not be in vacuum. Space habitats also have advantages over planets in that they're easier to move, they can be designed to not have adverse conditions like freezing cold, extreme heat and dangerous weather and you can build more of them.

If you step outside of Earth's atmosphere you're in the same vacuum, it's just a bigger step.

That's exactly it

> It would be so much easier just to create the ideal environment in a large, rotating cylinder instead of having adjust a planet's environment to our needs.

Yea but people want to go outside.

Artificial outside? If the ship, for lack of a better term, were big enough its conceivable that you could have a larger open area with grass and trees which would feel much like a park.

Could even paint the roof blue.

I’m open to it, but I suspect it would be difficult to figure out all the things we’d miss even on a biological level. You don’t think people would read about planets and realize what they’re missing? I think they would curse their ancestors for ever leaving. This feeling of leaving some paradise and forgetting what we’ve even lost is a core theme of genesis, it’s as human as anything in civilization, and it’s only going to get stronger if we explicitly abandon where we came from (I mean this metaphorically, I imagine we’d be happy on earthlike planets, even if we do miss earth’s sun or whatever at first).

I wouldn't be surprised if we develop brain uploads sometime in the next 400 years, at which point the focus on trying to recreate earth-like environments anywhere will look silly.

There's probably a lot of other advancements over the next few centuries that we can't imagine. Our current view of space colonization is probably going to have as much of a connection to the future as the Tower of Babel had to the Apollo program.

The concept of identity might change as well.

If your biological brain is you (to you only), then a digital copy is not you, it's a clone of you.

Also then, the only immortality we can hope to achieve is through those head jars so famous in Futurama.