Science Fiction Accelerator
Elon Musk is a character straight out of a science fiction novel. This is no accident. He has made it clear in multiple interviews that he has a deep love for science fiction. "Don't Panic" is gleefully emblazoned on the center console of the Tesla Roadster that is hurdling through space. He has actively used science fiction ideas to fuel the direction of his business life. Unlike other businessmen who prefer secrecy, Musk has publically stated his goal: Mars. All of his current business projects have phenomenal immediate terrestrial applications, but they are also stepping stones on his path to Mars.
SpaceX is the most obvious example of Musk's Martian obsession. SpaceX has explicitly stated that one of their goals is to go to Mars. In order to get there, it first has to develop high powered re-usable rocket technology, which requires capital, man-power, and resources. Fortunately there are many companies and countries that want to put things into orbit. Offsetting high cost long range rocket development by developing an orbital delivery company is a brilliant way to create the technology for an inter-planetary fleet.
Tesla Is Not a Car Company
Tesla is most famous for producing electric cars, but it is not a car company. It is a flexible electric drive-train company. A powerful electric drive train is crucial for the multitude of vehicles that will be needed to develop Mars for human habitation. Construction on Mars will require front end loaders, backhoes, dump trucks, and other construction vehicles with powerful propulsion systems. The Tesla Semi is the first iteration of electric vehicles geared to an industrial application.
Solar Power and Batteries
Solar power will be key to providing energy for most if not all of the required power for all of the infrastructural and living needs on the red planet. The Tesla Solar Roof is a cheap, thin, highly-modular solar power generation system. Storing this energy on Mars will require batteries. The Gigafactories are solar-powered battery production facilities that are designed to be energy self-reliant. They are producing Powerpacks for Tesla Automotive and building Powerwalls for consumer and industrial energy storage. The Martian Gigafactory will be modeled on these terrestrial examples.
Hyperloop and The Boring Company
Producing a range of powerful, electrically driven, battery fueled vehicles solves only part of the Martian transportation problem. Building anything substantial on Mars will require mined resources. It is unlikely that major ore deposits will be located near eachother. Transporting material to and from manufacturing hubs will require a reliable long distance transportation system. Extreme temperatures make long range transport on the Martian surface difficult. According to Wikipedia, the average temperature on Mars is -55 °C (-67 °F) with temperatures getting down to -153 °C (-243 °F) at the poles.
Most land-based resource transportation on Earth is still performed via train. Trains are efficient and relatively cheap. But Mars is different. A regular train-on-tracks would indubitably have many mechanical issues if it were exposed to the extreme variances of Martian weather. Even an advanced mag-lev would likely suffer from a slew of issues in such a hostile environment. In addition, insulating and heating surface transports for human occupancy will be very expensive.
What about flight? Propeller and jet based transport are hampered by the lack of air. Without planes or trains, transporting mass on Mars requires a different solution. The obvious answer is to go underground. The Boring Company is being created with the explicit purpose of making tunnel construction efficient and economical. Combine this with the Hyperloop and you get the efficiency of mass transport and the safety of sub-surface travel.
There are two additional benefits of cheap tunneling technology: mining and habitation. A direct derivative of The Boring Company technology will likely be sub-surface ore acquisition, with tunneling machines capable of chewing through even the hardest stone and ore. Subterranean living environments will also be cheaper and easier to build.
Elon is not only creating disruptive industries that are beneficial for the ecology of Earth -- he is also building a business empire whose core technologies have multiple applications for the colonization of Mars.