Somehow all of his projects tie together to build a full Mars infrastructure including solar energy, solar mobility, high speed tunnels, space travel and even that satellite network he planned to beam internet to earth from LEO. If he manages to do that in his life time and Mars becomes a popular alternative to Earth, his wealth (or that of his descendants) will exceed anything there ever was. Rockefeller, Carnegie, Vanderbilt and JPMorgan in one person. Of course, it's highly unlikely and just a though experiment at this point.
If all of Musk's endeavors amount to nothing more than just a means for a rich playboy to waste his time and money, it still makes me wish that more rich playboys had nearly as ambitious and constructive ways of wasting their time and money rather than spending it all on yachts, mansions, parties, and private jets.
At the very least, it is inspiring and on the face of it aims to make the world a better place for all humanity. That's a worthy goal, even if it doesn't work out.
I thought the Boring company was the most "obviously for Mars" project. One of the cheapest ways to create pressurized, radiation-sheltered spaces is to dig.
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