For Tesla it was "electrify transport to end dependence on fossil fuels and save the planet", for SpaceX it was "save humanity by becoming a multi-planetary species".
With how much he talked about it, he did probably actually believe in Mars.
But now both of these ideals have come into conflict with his newfound political affiliations, so they have to be dropped.
Remember when Elon said the Moon was a "distraction" and they were going "straight to Mars" [1]? That was only a year ago. At the time my guess was that a) Starship is just badly designed for being a lunar landing vehicle and b) the project is way behind anyway so this was just a way of kicking the can down the street. So what changed?
It's NASA's overhaul of the Artemis and SLS programs (IMHO) [2]. NASA wants to improve these programs by launching them more often and that, in Elon's mind, turns them into more of a competitor and takes money away from SpaceX. It's as simple as that.
I stand by my criticism of Starship: I think history will show it to be the Cybertruck of SpaceX. It's a poorly designed platform and it's beiggest problem is going to be that it has to compete with Falcon 9. It's going to be fantastically expensive to develop. It's still many years away from its promise (eg in-orbit refuelling) and there simply isn't the demand to get payloads that large into LEO or geostationary orbit.
[1]: https://x.com/elonmusk/status/1875023335891026324?lang=en
[2]: https://www.cbsnews.com/news/nasa-artemis-moon-program-overh...
Wait you mean Elon has been full of shit all this time???