Hint, SpaceX has an assembly line and is cranking out new starships and boosters every couple months while SLS will launch only every few years and then be chunked into the ocean with a hardware cost in the billions PER launch.
We don't have insight into SpaceX finances, but this should give you an upper bound on how much money SpaceX is spending on something.
This $10 billion in total investment and annual revenue has financed the development of Falcon 9, Dragon, Dragon 2 and Crew Dragon, Starship, launch pads at Vandenburg, Boca Chica, and two at the Cape, Merlin, Raptor, Starlink development, thousands of Starlink satellites, and all the associated ground infrastructure, recovery and recovery ships, and everything else.
While we don't have any hard numbers on what the Starship development program has cost thus far, it's not likely to be in the billions.
To do it they need around 6 launches for refueling in orbit.
The very upper limit on a single Starship launch is 0.5 billion.
Developing a working Starship is worth a lot to SpaceX. They could go deeply into debt on the first six launches, and make it up later.
And how SpaceX does pro-bono work for NASA in hopes of ripping them up later.
How NASA, Jeff Bezos, Government Accountability Office as well as courts are blind to it.
(Bezos already dragged NASA trough GAO and courts with regard to HLS)
And Musk is doing that instead of doing it in the honest and straightforward way like Bezos by just lobbing the Congress and asking for a lot of money.
Or you could just accept SpaceX track record on space programs and that SpaceX delivers cheap services.
For SLS, the hardware cost alone is 1.5 billion. Starship has development cost, but I can guarantee you that the pure cost of ordering the hardware didn't cost 1.5 billion $.
And this is not even a possibility with the non-reusable SLS, which makes continuing it seem kind of crazy.
https://www.cnbc.com/2022/02/11/elon-musk-spacexs-starship-i...
Do you have a source behind your estimate that a fully reusable Starship launch is over 20x the cost of a partially reusable Falcon 9 launch?
To do it they need around 6 launches for refueling in orbit.
The very upper limit on a single Starship launch is 0.5 billion (2.8/6).
The more launches, the cheaper Starship gets.
To do it they need around 6 launches for refueling in orbit.
Therefore, the very upper limit on a single Starship launch is 0.5 billion (2.8/6).
And that's without development cost of Starship HLS.
Single SLS launch cost without Orion, including development, will be around 4 billion dollars.
20 billion overall for SLS development + 20 billion for Orion development.