And that's why I posted those article links on the other thread.
It is easier to build a "colony" inside a huge cave on earth than it is to build a rocket or ten and send what is needed to Mars.
It is easier to keep those people alive in that cave on earth than it is to maintain shelter, air, heat, radiation shielding, etc on Mars.
It is easier to return to the surface than it is to leave Mars to come back and reclaim Earth
I would agree that it is easier to do all of the things that you suggest and on the other hand the technological advances that we would achieve by doing the harder option could also be used to improve life on Earth as well.
I mean if we perfected a Fusion reactor for a Mars base then we could also use that Fusion reactor on Earth and essentially eliminate carbon production from our current energy sources and have essentially free energy for everyone on Earth.