It was a simpler goal than that.

From the first paragraph or two of https://en.wikipedia.org/wiki/History_of_SpaceX

> In August 2001, Musk shared a plenary talk with Mike Griffin at the fourth Mars Society convention where he announced his plans to send his greenhouse to Mars.[6] In October 2001, Musk travelled to Moscow with Jim Cantrell and Adeo Ressi to buy refurbished Dnepr ICBMs that could send the envisioned payloads into space.[7]

Elon got the Mars idea from Griffin.

IIRC originally Elon wanted to land a greenhouse on Mars, not people from the very start.

Establishing a massive functioning greenhouse on Mars, before sending people, still seems like a smart idea to me.

In fact, setting up as much automation as possible, pre-people, would be a good way to establish the human safety of Mars flights.

As well as supercharging the productivity and quality of life of the first Marsers when they finally do arrive.

IIRC the very original plan was a small glasshouse with a camera. But your idea sounds good as well. :)

Why would the Russians laugh at that? They did this themselves.

https://en.m.wikipedia.org/wiki/Dnepr_(rocket)

They were not laughing because it was an impossible idea. They were laughing because they have seen an opportunity to part a rich person from his money.

Or laughing because it was absurd, Griffin was CIA. The US had just left the Anti Ballistic Missile Treaty, and so it was obvious to everyone they wanted to develop low cost launch for a Brilliant Pebbles reboot. Now it's finally happening.