A multiplanetary species is simply not going to happen, since there are no plans to figure out a way to not make your blood boil (literally) on the surface of Mars or the Moon.
Except for the multiple studies exploring how to build habitats on mars/moon and how to build spacesuits that would function on mars/moon.
Listen, I get it. We're not going to have a million person utopian colony on Mars in 2026. That doesn't mean we shouldn't try to shoot for a small 4 person colony in 2032 to start doing research. This is currently our most promising way to get there.
Did you know that there are many activities that you can do on the Earth that, without appropriate technical equipment, are fatal? From diving to mountaineering or living in deserts, mankind has overcome many challenging environments.
I know, I am a decent scuba diver. Any of those activities is not something you do 24/7/365. Even underwater it takes more time to die than on Mars (where it's instant as soon as the airlock fails).
Consider the Tibetans who evolved unique genetic adaptations that allow them to better survive in the low oxygen environment of the Himalayas. Or the Inca, who developed specific architecture and agricultural technologies to deal with the high winds, limited arable lands, and harsh weather in the Andes. These are dangerous environments that supported a significant population 24/7/365.
Progress happens iteratively. We figure out how to get there first, we'll - or future generations will - figure out how to live there comfortably. Dead cats and birds, well, small price to pay for getting us off this rock.
