>At least on Mars, you could potentially do mining.
You can also take that idea further and just do mining in space. One of the most interesting regions is simply cislunar space. Human development there means you can haul asteroids in, you could potentially move polluting industry there, do science in environments that you can't do on earth, and so on. It's much safer than being stranded far away, it's relatively easy to get people back to earth, etc.
The entire idea of going to another planet simply has the huge problem that you need to waste a ton of energy to get things off the damn planet again so really why not just built habitats in space.
This is exactly my position. It would be easier to just build habitats (like O'Neal cylinders) in space that have the exact parameters you want, rather than trying to terraform worlds like Venus to be somewhat-habitable after millennia.
And yes, asteroid mining looks very promising. Facilities on the Moon might be good for this industry, by providing a place with some gravity to do work, and not be worried about environmental issues (or an atmosphere to get in the way of transport). And it's not far from Earth, so you can take all the products of asteroid mining and easily ship them to where they'll be used on Earth, or launch them out into orbit to build space habitats.
> you could potentially move polluting industry there
The reason industry pollutes is that they either DGAF, or it's part of the process. Those industries either won't care to move to space in the first place, or the re-design of the whole process would have been better spent improving the process on earth.
You can also take that idea further and just do mining in space. One of the most interesting regions is simply cislunar space. Human development there means you can haul asteroids in, you could potentially move polluting industry there, do science in environments that you can't do on earth, and so on. It's much safer than being stranded far away, it's relatively easy to get people back to earth, etc.
The entire idea of going to another planet simply has the huge problem that you need to waste a ton of energy to get things off the damn planet again so really why not just built habitats in space.