I wasn't aware we had a launch site on Mars?Then launch from Mars to the next destination.
We have water, oxygen, roads, heavy plant, scientists and great deal of other things here on Earth and launching humans into space is still extremely difficult. What on Earth makes you think we can achieve that on a barren inhospitable planet, three years round trip away from Earth?
Each time you do the maths, the difficulty leapfrogging onto the next planet rises exponentially. Earth does not have the resources to colonise another planet.
