Dude! I freakin' LOVE space.
I just know enough about it to rankle when people act like the solution to climate change is to move on to the next planet. (Believe it or not there are people who actually think that it can be done! Drives me nuts.)
Yeah the whole "we need to settle Mars as a backup for Earth" is plainly silly. You could wait until global warming took its course for the next century, and even if it far exceeded the worst case projections, we continued to abuse the environment and annihilate habitats, and we had a few major nuclear exchanges in the meantime, it would still be many orders of magnitude easier to terraform Antarctica into a comfortable place for millions to live than it would be to make the slightest dent in the radioactive frigid atmosphereless hellscape of the Martian surface.
I'm not saying we should do any of those things to the Earth, nor am I saying it's not worth it to try to make a go of it on Mars, at some point, at some scale. Just agreeing that in no way does teraforming any other planet represent a comprehensible fallback plan for ruining our own planet, quite aside from that being a defeatist and morally repugnant thing to do in its own right.
First of all, let's clarify some things. Branson's flight was a Vomit Comet. That's all. Spaceship Two doesn't reach the Karman Line. It's the TWA plane from 2001.
I do agree with this, and in fact I expounded upon that myself at some length in my first post in this thread. So yes, we agree on this point specifically.
I'll answer other points that you make that seem salient, though a lot of them like "define the economy" seem a bit nitpicky, and would send us down an internet forum rabbit hole of definitions and off-topic discussion to respond. So if I don't answer a point it's not because I'm ignoring you, I just want to keep the focus of the discussion vaguely on-topic.
Four, is "the economy" more important than the ability of the planet to continue supporting 8 billion human beings?
I don't agree with the premise that it is a binary choice. I think it's possible for us to address the awful ramifications of our exploitation of the planet while simultaneously doing other things, like space research or fine arts education, to name 2 sectors of the global economy with approximately similar expenditures.
Five, what type of economy are you talking about? Are you talking about the continuation of a consumer economy predicated on the manufacture and sale of semi-disposable goods? Is "the economy" of which you speak sustainable for more than the next 50 years?
I'm not gonna really touch that, except to say that no, I'm not trying to promote space development as some kind of Trojan horse for expanding late stage capitalism in order to twirl my mustache evilly. I support space development for its own sake, irrespective of the social or economic or governmental system under which it develops.
I certainly have favorites and less-than-favorites in all those categories, but they aren't really germane to the topic of whether space investment is worhtwhile.
Six, is the benefit to "the economy" from reusable rocket technology a greater benefit than the benefit to "the economy" from climate mitigation and environmental research?
Even if I accept your premise that space development is of less value than climate change research (I'd actually argue the 2 are synergistic), I still think there are literally hundreds of industries from sports to jewelry mining and manufacture to wasteful spending on military might from which it makes more sense to redirect resources. Those industries cost way, WAY more than we spend on space, return less to the real economy, and are arguably an active bad as opposed to a lesser good for sustainable use of our planet. And they are just examples among hundreds of examples you can find.
So, inasmuch as I do not believe that space exploration represents a net economic positive over climate research and development, your basic premise fails.
And I do believe it is a massive net positive with a potential to be a history redefining positive in the next century or two, so we simply disagree here.
Seven, are either of these approaches moral where such would almost certainly come at the cost of millions, if not billions, of human lives and the extinction of countless species?
I don't accept this premise either. The idea that investing at our current or higher levels in space development will ipso facto lead to billions of deaths is... well the word "hyperbolic" comes to mind.
The cart, right now, is in front of the horse. Until we can learn how to continue to have life on Earth, I say that space races like this are wrong. They do not substantially advance the existing research while simultaneously promoting the wrong belief that the immediate dangers to life, and yes, the economy, are less important than some vague undefined idea of space colonization.
This is basically the thrust of my entire response, but I'll encapsulate it here. Humanity is capable of walking and chewing bubble gum at the same time. It is NOT the case that we live in a zero sum world in terms of research, where every dollar spent on one line of research could be diverted to another and provide a 1 for 1 improvement in research progress. You can increase investment in certain lines of research to improve progress, but at a certain point you reach a point of diminishing returns. You can't double investment to double progress ad infinitum, and in fact advancements in one area often fuel advancements in another out of proportion with the actual initial investment...as is the case with space development disproportionately benefitting climate science and earth sciences in general. So while I sympathize with the urgency with which we need to address climate change and other environmental catastrophes here on Earth, I simply don't find the argument that because we have problems there, we can't invest in anything else at all worthwhile to be very coherent or convincing.