That's the Musk Myth.. in reality SpaceX was built by Mike Griffin who (1) funded him through In-Q-Tel and DARPA (2) crafted the commercial crew program for him while he was NASA administrator.

He even went with him to Russia before SpaceX was founded,

https://wikipedia.org/wiki/Michael_D._Griffin

pretty big stretch to give that much credit to Mike G given what's known about history of spacex

Care to elaborate?

Mike G also started the Space Development Agency, with a goal of funding govt LEO constellations with specifications matching Starlink.

Him or others? What about the people he is firing?

Regardless, businesses don't care what you did in the past - for that, your reward is your compensation - you are hired for what you do tomorrow.

> he kinda built it with his blood sweat and tears.

Irrelevant to being hired or kept on as the president of the company by the owners, of which Musk is only 17% (AFAICT). If more owners of the company do not want him as an employee (president, whatever), then they can fire him.

Whether that would be a good idea or not is something else. (Apple 'fired' Jobs in the 1980s.)

According to wiki, he has 47.4% equity and 78.3% voting control according to a 2020-dated filing. I would be surprised if either number has changed significantly since.