you're right that settling mars seemed impossible for the last 20 years, but that's not so much because of the toxic dust or the radiation or sth; but simply for financial reasons.

basically, as you've already said, it costs a lot of money to do this. and the question is: is it worth it? the question has always been a resounding "no" since the 1970s, but things are starting to turn. the reason is because while the costs are high and the reward is small, it is still positive. self-sustainance can be achieved 99%, it does not have to be 100%, you don't need to produce computer-chips on-site from the get-go; you just need to reduce the mass of necessary imports low enough to make it worth-while. say if people could just produce water and food and maybe some plastics (3d-printing) on-site, that would already cover more than 95% of their import mass, i reckon, and that would make sustaining the whole settlement a whole lot more feasible.

now, about finances: capitalists are constantly looking to invest into the next branch of the economy that promises growth. for decades, this has been computer stuff and similar earth-bound technology because it promised a higher return-on-investment than some astronautics project. but that is starting to turn as it is becoming increasingly clear that IT is a bubble today (AI bubble) and there's economic stagnation threatening all around us. so the economic system will naturally seek to explore new fields that are not bound by the space constraints of Earth, and i think that if you look at it this way, space settlements are not just a wet dream but an economic imperative. (in the sense of, some economics professor will look at this and say "we have to do this").

the dust on-site is less of a problem, i guess, because there's toxins in the soil on earth too. you're not supposed to just eat dirt that you find in your garden because it can contain toxins from bacteria and you can suffer from that. however, we still live just fine on that soil. people have managed to live in the sahara desert and in the midwest as well (where dust storms occurr regularly, i think). with technology, the western edge of the midwest, where it borders into the desert, is actually one of the most agriculturally fertile regions on earth these days (center-pivot irrigation article mentions it).