There are no self-sustaining Arctic settlements - i.e. Ones that grow their own food locally without hunting and without getting regular air drops, generate their own electricity, de-salinate or thaw their own water etc, create their own fabrics and building materials, and have some options to create their own microprocessors if needed. Oh, and that can launch its own rockets to space.

Musk is purportedly dreaming of a colony on Mars that would survive if the Earth were destroyed. That means that not only do they need to grow food, get water and generate electricity from Mars, but they will also have to have the manufacturing capacity to make everything from tunnel boring machines to microprocessors. An actually self-sustaining colony on Mars would likely have to be closer in size to a large city on Earth than to a permanent base in Antarctica.

Even a large city today doesn't do most of those things. How many microprocessors are fabbed in London, rockets launched in NYC, or lumber harvested in SF? This seems like an unreasonable standard to measure by.

Well, can you imagine a colony that could survive indefinitely if the Earth were destroyed (Musk's stated goal) without having all these things? If they couldn't build another water processor chip, how long would the colony last?

So I would look at it the other way: even a large city on Earth isn't entirely self sustainable. How could we hope to build a self-sustaining colony on Mars in 60 years?

Yes but regardless, I'm not going to pursue the fools errand of defending an elon musk schedule. That wasn't the bit my comment responded to. I simply pointed out there are already many permanent arctic settlements, and you came back with new goalposts that no city on earth meets.

"self sustaining settlements" was the goalpost

Yes, and again we're talking about the high arctic Inuit, one of the most historically self-sufficient groups out there. Like most other people on the planet, they don't produce a lot of microchips, but they've spent the past millennia or so producing everything else they needed out of what was available in the local environment.

The Inuit are self-sustaining by the standards of humans living on Earth, but they are in fact dependent on a huge, globe-spanning ecosystem for all of their food. Even disregarding the problems of high-tech required on Mars, they are not self-sustaining in the sense we were discussing here - they wouldn't be able to survive if the rest of the earth were barren.

But of a shot in the dark here but anyone know of good sci fi books from the perspective of someone colonizing another planet after their original plant died and humanity not having sufficient resources to maintain earth’s development rate?

Or, that sort of area.

This isn't exactly that, but there's https://www.amazon.com/gp/product/0451116534 for struggling colonies in space.

Large cities are not sustainable by themselves. They need the rest of a country to keep them alive. Really, this whole thing is a pipe dream.

SpaceX has done wonders for getting the cost of moving a kilo of matter into orbit. From a tech point of view it is a very large but still incremental step from where we were before.

A self sustaining Mars colony is science fiction.