Is it really necessary to send humans to those places just to get the knock-on benefits? Couldn’t we do those things directly, without going there?
It seems to me that, today, those who have the money to spend on these endeavors would only do so if there were perceived short-term benefits to themselves. That means they plan to exploit the resources, or increase their own power somehow.
I know the good engineers that make this happen are doing it for the challenge and in the pursuit of knowledge, and I know that’s why we poors support it, but that doesn’t “pay the bills.” What is the motivation behind the money? Why are they really doing this?
I’d separate this into two different things - what is good for humanity and what is good for billionaires like Musk.
For humanity, venturing out into the solar system will advance science, and also help drive technological advancement which does have benefits for society as a whole. The space race in the 20th century did advance technology, and much of the modern technology we take for granted has routes in the space race.
But also humanity needs to move away from our current capitalistic system and that is very much driven by scarcity. The resource wealth in the solar system is mind bogglingly vast and if we can tap into even a portion of it, it could allow us to change how we as a species live. It would initially be driven by capitalism for sure, but when you have effectively infinite resources for a civilization, that changes everything we do.
Also for the long term survival of our species we need to be looking outwards. Earth is vulnerable - one asteroid strike and out species could be wiped out. Even if only a small number of people were to head out into the stars, it would help guarantee a long term future and resilience for our species.
I think one big mistake people make is that what happens on earth is a zero-sum game: i.e. for some to win, it must be at the cost of others. That is wrong and is a result of our terribly broken economic system. But we can both colonize the moon and mars AND fix the problems on Earth. And it may do good for our species to look up to the stars and have a bigger shared goal than just existing on this rock and acquiring wealth.
In terms of why the moon & mars. The moon is essential as a staging post for future expansion, as it’s very expensive resource and energy wise to launch from Earths gravity well, but much cheaper to build at the moon and launce from there without the added step & complexity in design for launching off Earths surface. Mars meanwhile is the most viable candidate at present for a self sustaining colony long term (with a couple of moons of Jupiter and Saturn other options, and possibly venus as a long stretch).
Meanwhile, Musk is a deranged billionaire idiot. He is nothing more than a investor gambler; other people are doing the hard work making things happen while he is a public face of various companies. He really is peripheral to this, even if he does push the topic into the public consciousness. Don’t conflate the idea of expanding into the solar system with that idiot. The idea precedes him and will run long beyond his life and any influence he has. He is just a narcissistic loud mouth with money.