This is a well-studied topic, of course. The primary economic value is tourism/novelty. There are not large amounts of helium-3, like on the Moon, but there is

This is a well-studied topic, of course. The primary economic value is tourism/novelty. There are not large amounts of helium-3, like on the Moon, but there is ice. If you can get there (SpaceX in particular is working on that, for $500,000 a ticket), you could potentially live in a spacious, bomb shelter-like structure with relative comfort, and even venture outside (with a spacesuit) if you felt up for it. Mars could become a retirement locale for the sufficiently-successfully, not unlike of Florida but without the gators. It is not particularly likely, even with reusable rockets, that ore would be worth the price of shipping back to Earth in bulk. More efficient to use it for cheaper spacecraft (launch from Mars is less demanding on fuel) or Mars building structures directly, to house more residents.