If you looking at building a civilisation on Mars that is going to need the transport of landers to carry/be housing, factories, machinery, food, materials etc a regular shipping fleet will be needed. Many of those ships will be one way tankers and freighters.
You are looking at space moving from a scientific to an industrial basis.
Meanwhile, even as we wait for Starship V3 first flight, V4 is being designed.
Musk:
Starship 4 will be another 10% to 20% longer.