Then you don’t get Elon Musk. Elon Musk will sell Tesla long before SpaceX. He cares a lot more about SpaceX and that is the company he actually founded. Tesla was a small company he bought. SpaceX is much more of his baby.
And Elon Musk’s goal is not to build a large car company but to electrify transportation. That does not need to happen with him at the helm. Musk knows he could sell Tesla today and it would continue to be successful and if not there are plenty of competitors making good EVs.
The same is not the case in the space industry. I company is on track to make humans multi planetary and thus SpaceX is a company he cannot let go.