SpaceX at the moment just wants to get people to Mars, building the colony beyond a landing pad and propellant depot is left as an exercise for the passengers.

SpaceX at the moment just wants to get people to Mars, building the colony beyond a landing pad and propellant depot is left as an exercise for the passengers. When they land the first two BFRs on Mars, I think we will see enough people willing and have the means to build a colony. Until then, it would be hard to get people to commit the needed capital.