I grew up in the 60s, and after the moon landings, they were promising space bases and Mars colonies in a few years.

Scientists have stopped promising this, because it's obviously very hard, but even in 2024, a lot of people honestly believe that we can kill the Earth's biosphere and simply move to Mars and make the deserts bloom. It's literal madness. If we can't keep the one ecosystem we know of alive, how can we possibly create a new one from scratch? (And any sort of rational time/money estimate ends up with it taking at least decades and quadrillions of dollars...)