It's because they've convinced themselves that without full self-driving Tesla is worth nothing. Certainly it's the only thing left to justify the stock price:

https://electrek.co/2022/06/15/elon-musk-solving-self-drivin...

Musk has been lying about full self-driving for nine years now. He pointlessly backed Tesla into that corner:

https://jalopnik.com/elon-musk-promises-full-self-driving-ne...