That will never not be true. There will always be room for improvement. In fact, the moment we don’t have anything to improve on Earth is the time we shouldn’t expand outward, as by that point we’ve probably become a society of narcissists that thinks we’re perfect and can do no wrong.

And moreover, expanding outward helps us protect Earth. We should be trying to move as much of our industry offworld as possible. Most of the universe is not a place we can “ruin.” There is no way to irresponsibly use a dead asteroid. There’s nothing to “take care of.” The only biosphere in need of protection that we know of is Earth’s. That’s half the point of space colonization - giving us space to do a lot of the things that really shouldn’t be done on a place as delicate as Earth. You can’t pollute the Moon to be more lethal than it already is. It’s already a barren, airless, radiation blasted hell hole.

Humans aren’t Captain Planet villains. No one pollutes for the sake of pollution. Pollution is always the negative byproduct of something else. And a lot of those industrial processes would best be moved off Earth in the long term.

I don’t think we’ll ever be perfectly responsible. If we turn Mars into a paradise and later wipe it out through our idiocy, well at least it had a brief time as a living world. But that’s fine. We can expand outward and turn a million dead worlds into a million living worlds. Will some of those new Edens later be driven to ruin by our own flaws? Certainly. But even if half die off, I’ll take 500,000 new Edens over a 500,000 barren rocks.

Those who wait for the perfect time to act die of old age before they ever accomplish anything.