Is re-use an essential component?
OK, I get that re-use makes a whole lot of sense for the booster stage, I mean it does have 39! expensive Raptor engines, plus all the bits to power them.
But does Starship need to be re-use?
What if that part was eliminated, could Starship contain all the modules required to go there, land, take-off and come back safely?
Look at Apollo, it went to the Moon, landed and came back. You could probably get a few Apollos in the Starship....
Then the astronauts may get to Mars and realise it's so bloody inhospitable/dangerous etc that returning is not worth it.