You can distill the water using solar energy, even without converting it to electricity beforehand, which insanely increases the efficiency. Also, it just requires some initial materials, and then the process basically runs itself. It absolutely could be done at a large scale, especially in places where there is much sun and much saltwater (equatorial coastlines), but the process is veeery slow and there is not enough demand for freshwater (yet) to warrant the construction of gigantic solar stills. As a bonus, global warming increases the efficiency of the process AND the process cools the Earth down somewhat (separating the water and dissolved stuff is a thermodynamically entropy-decreasing process).
That is true, but a "debilitating mental disorder" means completely different things to every person. So, you should go to therapy if you feel you need it, which means that trying to decide for someone makes no sense at all.