As I understand matters, Mars has apparently lost a large fraction of its estimated water from the time of formation, but still possesses very large quantities not only at the poles but at considerably lower latitudes too. MAVEN, our most recent orbiter, is expressly designed to investigate and quantify how water and other volatiles get lost to space there. I think the European orbiter is also pursuing this line of research.
I gather that most of the water presently near the surface but not at the poles is in the form of dust-covered ice.
It's clear that Mars has many resources that would facilitate construction of a scientific base, and perhaps, much much later, something bigger. I see no business case for building anything much on Mars though. There is nothing there we can't get here for a fraction of the price. This is the issue with all space-based industry as far as I can tell.
There are some chemical processing operations like electrophoresis and crystal growth that work better/differently in microgravity, so in a world where the cost of launch services has collapsed (thank you SpaceX), that might open up some new business opportunities. Scaling that up, however, is an unsolved problem. One that doesn't benefit from human presence either I might add. it will all be robotic.
I find the case for human exploration of Mars a difficult one to justify. I might add that as a member of the "Apollo generation" I have always been fascinated by space exploration and related science activities. Hugely fascinating and also worthwhile. What we have learned in the past 20 years alone about the early solar system formation, the formation and evolution of Earth and the rise of life here is mind boggling. Finding a second genesis anywhere would completely re-write our understanding of our place in the universe, at least for those of us willing to entertain those findings. No doubt there would be no shortage of skeptics.
As I noted in an earlier post, pursuing the exploration of Mars in the name of elucidating our understanding of our evolution and history is a worthwhile enterprise. But unlikely to be one that garners Apollo-like funding. No, I don't believe that you have to send astronauts to do this research. Clearly not. Every rover generation sets a new standard for what we can do remotely. Human spaceflight is oversold.