We can't keep astronauts aboard the ISS indefinitely, even with constant restocks from Earth, and we're supposed to go even further out of our orbit to the moon or Mars and they're going to be fully independent?

And even so, that might be the easiest part of the whole terraforming thing. It only gets worse from there.

The closest thing to a self sustaining thing is that Neom city they're trying to build. It's basically an arcology. And it's already failing.

I gotta imagine making the Sahara Desert habitable is a lot easier than making Mars habitable. The Sahara at least has breathable atmosphere, a 24 hour day, solar intensity that our plants are well adapted to using, and is relatively close to resupply from population centers on Earth.

Yeah, I won't knock people trying to leave the earth. I work in space stuff, and I would love nothing more than to see us realize multiplanetary habitation. but I definitely think we need to be good stewards of our planet. We don't exactly have a plan b. And realistically, we may never have a plan b. Science is hard.