Economically, I think one huge advantage the Moon has over Mars, is tourism. The Moon is a practical tourism destination because you can spend a few days there and be off-planet for less than 2 weeks. Billionaires can take the time out of their busy schedules for a few days on the lunar surface. Mars is not a practical tourism destination because a minimum round-trip to Mars is closer to 2 years than 2 weeks. Nuclear propulsion may speed up the journey but even then it is still going to take many months.

Once you get regular tourist trips to the lunar surface for the ultra-wealthy, the economies of scale can drive down the cost and grow the market, and you may have the self-sustaining economics for a permanent lunar population to support these visiting tourists – hospitality staff, tour guides, maintenance staff, medical, construction, spacecraft maintenance (vehicles like HLS Starship can't return to Earth for maintenance but that could happen on the surface), etc.

I don't think it has to be either/or, you can do both – establish a crewed research station on the Moon and establish a crewed research station on Mars. But the former has a much shorter path to evolve from a research station (which is dependent on public funding or private philanthropy) into something economically self-sustaining than the later does.