The man is gifted. My 11 year old son saw the SpaceX video on Mars. He said 'that's where I am going' .. see I believe Musk let the cat out of the bag in terms of ideas.

See he's building a rail road within the solar system. He's placing his bets on asteroid mining taking off, and the logical place to mine would be the asteroid field.

Mars is literally next door. Allowing you to mine and come home to Mars. With 1/3 the gravity Mars allows you to do some things that you might find daunting on Earth.

Such as building a space elevator.. which is feasible with today's technology on Mars but not Earth.

A space elevator would allow for processing large amounts of raw material on the surface, allowing for larger populations to grow (for both mining, transportation and processing). At a certain point people there would want Coffee Shops, Stores, Restaurants to spend their income.

The problem was transportation. If transportation is fixed in the next few decades then wow... we're going over the whole solar system.. and Musk is part of the reason.