He writes "It is ultimately much easier to journey to Mars from low Earth orbit than from the moon".
His argument is completely different and unrelated and not the point at all.
No-one is arguing about where to start a journey to Mars from. The point is that settling on the Moon is an obvious first step.
Yes it is.
What benefit do we get from this?
It means we could go there more frequently. I don't see why that itself is reason enough for it, once you consider all the other pros and cons.
It does not mean it requires less fuel to get there. The fuel requirements are primarily for getting into orbit. Once there it doesn't really matter the distance you travel.
> It is obviously a much better ground to learn to live in a self-sustained way on another planet.
It is not obviously so. The wikipedia link I provided goes into this a bit, and Zubrin goes into much more detail in his book.
If it's so obviously better, why don't you outline the reasons why it's meant to be better.
> The point is that settling on the Moon is an obvious first step.
But you haven't argued this point, aside from saying it's closer to us and asserting that "It is obviously a much better ground to learn to live in a self-sustained way".