Actually space is (probably) infinite, so there are potentially infinite ressources avaiable, if we choose to invest in the next step, even if that investment only will pay out in the long run.
I am not an astrophysicist, but my understanding is that due to the expansion of the universe and the speed of light, the volume of space we will ever be able to access is finite, roughly that of the galactic supercluster we're in.
For all practical matters, I think it can be considered infinite. (And the theoretical limits might not be fixed either)
But the question is always, how much of that is within our reach.
Currently nothing out of earth on an economical base. So I also see the point we have to set priorities.
But currently there is a big focus on war, rather than climate change etc. and with more crisis, people tend to think even more short term. Space on the other hand can give that long term thinking effect, that can people make consider whether fighting for the limited ressources on earth is the only way. And maybe instead unite forces for benefit of all of mankind (and possibly life itself).
This isn't even close to true. In addition to what the other comment points out about eventually losing causal contact with all parts of the observable universe that aren't already gravitionally bound to the same supercluster as the Milky Way, even something like breadth-first search of the entire local supercluster at near the speed of light would take more time than the local supercluster will still exist. The universe will run out of hydrogen and stars won't exist any more long before you can cover all of even the tiniest portions of infinite space.
No. For all practical matters, accessible space is FINITE, and actually gets smaller all the time due to accelerating expansion of the universe. In about 150 billion years all galaxies outside the Local Supercluster will pass behind the cosmological horizon.
"For all practical matters, accessible space is FINITE"
I think, this is what I said:
"But the question is always, how much of that is within our reach."
Currently that is only earth. With some steps up, you can have all the other planets in this system plus the asteroid belt. Step further up and you have lots and lots of other star systems, the cosmological theoretical limits you are citing are not really an issue on the timeframe that matters to us - space tech is and the limits how fast we can make rockets, or find other ways to take a short path.
The particularly informed of humanity are very commonly wrong in their assessments, persistent underestimation, of the speed of change and what actually changes. It's because very few people know how to think effectively.
Failures of extrapolation are most often the cause; not understanding how to think properly, tripping into 2D thinking (extrapolating via some magic forward line, thinking that's how things actually work in reality) and bumping into ignorant logic failures over and over again (associating progress on one thing into broad assumptions that everything of course will progress just like that too, when the things and their potential for progress aren't so tightly bound).
Because X thing progressed rapidly, of course we'll have flying cars in 30 or 50 years. One of the classic failures of ignorant flat thinking of the 20th century. People should ask more questions.
Nobody has proven that they can predict the future reliably, and I doubt anyone can. They'd be golfing with Warren Buffett if they could. For one, predicting the future requires intimate knowledge of multiple disciplines. A space expert isn't going to understand computer chips well enough, for example.
In the 1970s it was also popular to fear grave resource shortages here on Earth. Turning to space was an easy low-imagination solution when you weren’t seriously considering the logistics of how to make it happen. It’s more a manifestation of the fears of the day than anything else.
This shortages haven’t really materialized. If anything we have far too much oil, not too little, and can keep on burning it for a long long time (and suffering consequences). Minerals for your car batteries? We can have lots by just seabed-mining right next to some sensitive ecosystems. Etc, etc.