alt Hacker NewsWe're not escaping Earth nor seeking to replace it. The entire idea of becoming a multiplanetary species is exactly that. Ostensibly we all started in Africa, and plenty of us are still in Africa. The same will be true on a planetary level, and eventually on a star system level. You said a lot and I don't want this to turn into a wall of zig-zagging tit for tat nonsense, so I just want to speak briefly and holistically. The first missions to Mars will be fully dependent upon supplies we're bringing. The goal of self sustainability is aspirational and long-term. At best it will take decades. In reality, it may never happen much in the same way that no country in the world today is fully self sustainable in practice, even if many could be in theory.
The whole point of the extended stays in LEO are precisely to simulate worse case scenarios for travel to Mars. So for instance the record for the longest time in space is held by Valeri Polyakov. [1] He spent 437 days on Mir in LEO, and then opted to immediately walk upon landing back on Earth. It was all to prove that humans would be physically capable of working on Mars (which has 1/3rd the gravity of Earth) even after absurdly long periods of time in space. In fact his first words upon return from his first (240 day) stay in space were "We can fly to Mars."
Robotics don't really work well for space exploration, because moving parts break. For instance the Curiosity/Perseverance drills are cutting edge yet have a max depth of ~2.7 inches. And traveling is even harder. On average Curiosity ended up traveling about 1 mile per year. It's all because if anything breaks, that's game over. So everything has to be done with the utmost of caution, and even then stuff constantly breaks. Curiosity's drill broke after about a dozen activations and required a team of scientists and months of full-time work to create a passable work-around when it could have viably been fixed on the ground by a human in a few moments.
This is part of the reason that we only learned in 2013 that the soil/regolith on Mars is actually extremely moist, 2-5% water by volume. A cubic foot of soil heated up gets you about 2 pints, a liter, of water. The whole plot-line in "The Martian" about having to jump through hoops to get water was correct based on the latest knowledge when the book was written in 2011. We'll probably learn more in a couple of weeks with people on Mars than we have with 60 years of probes and rovers.
I'm certain every human of sound mind is grateful for Earth. That's not a reason to not seek to expand out as far and as wide as we can.