Whether it's economically a good idea, I don't think it is, at least not right now. People want to do it primarily because it's cool, not because it's useful. (There's also the cynical view that Elon is hyping it up in order to induce demand for his own company, which seems plausible to me given that his arguments about X-risk are so transparently wrong and he's even admitted as much in the past.)
However, once the first settlements are established and the sunk costs have already been paid, it will be much easier to make them an economic positive. It's also possible that we get a space race 2.0, as other superpowers like China become concerned about the US establishing a dominant interplanetary presence and try to create their own.
That's my point; that is explicitly not the plan. Elon wants to establish a colony right away, and he's in the process of building up the infrastructure to do it. Frankley I think it makes no sense to compare the two; the US went to the moon as part of the cold war with the Soviet Union; the whole point was just showing off. The Apollo program was much too expensive to support a long-term lunar colony, and there were never serious plans to do so. The current space race is completely different. Elon is not trying to compete with anyone. He just wants there to be a civilization on Mars, and unlike the Saturn V, Starship is designed to be cheap and reusable enough to make that possible.
I haven't yet read A City on Mars, but I've heard that it's pretty poor. e.g. Peter Hague's review: https://planetocracy.org/p/review-of-a-city-on-mars-part-ii.
I'm wondering whether it could be worthwhile to establish a new humane animal product certification. Many words have been written on the EA forum about how the existing labels like "free range eggs" and "pasture-raised eggs" still involve horrific conditions for the chickens, and it's best to avoid them entirely. But eggs, along with other non-meat animal products like milk, wool, and honey can in theory be produced completely humanely, it's just much more expensive. A EA-aligned certification body that actually cares about animal welfare could maintain a list of producers from whom it's ethical to purchase.
Obviously factory farms wouldn't be interested since it's less profitable, but there are at least a few hundred thousand people in the US, probably a few million, who seriously care about animal welfare and would support a niche brand like this. (This is many more than just people in the effective altruism movement; think about the people who produce documentaries like Dominion.)
I'm thinking it could start by appealing to small family farms, like people who have a single chicken coop in the backyard and supply eggs to their neighbors from time to time. Come up with a comprehensive guide to producing animal products ethically, make it available online, and advertise it to small independent producers. Then offer to have someone visit their farm in person and check the conditions, providing suggestions for improvement if any are needed, and if the criteria are met, add them to a list of certified producers. This would obviously be expensive (at least $1000 in travel costs alone), so subsidize it with EA donations at first, and then as the brand catches on it can start charging producers.
Make the list easily searchable to put buyers in contact with sellers. e.g. personally I don't eat eggs, but if I could search for ethical producers in my area, I'd be happy to drive for an hour and pay 5x the normal price to pick some up.
Alternatively it could maybe start with non-perishable items like wool, since those can be shipped long distance to people who want them, so it makes more sense for a product with an extremely small number of producers. (But is there really anyone who desperately wants wool instead of synthetics and would pay a premium for ethical sourcing? Not sure.)
I'm curious whether this has been looked into before, and if so, why it was decided against. I feel like there'd be an opportunity here to partner with more traditional animal rights groups and "back to the land" groups, while also supporting EAs who would like to consume ethical animal products, and raising awareness in the general population of the insufficiency of the existing standards like "free range eggs".
A location doesn't need to be "better" for it to contribute to the economy. Some countries are almost strictly worse than others in terms of natural resources and climate for living and growing things, but people still live there.