The CEO is chosen by the board, which is chosen by the shareholders. The shareholders have the ultimate power, if they can unite on a goal/decision. Overwhelmingly, the only thing they can agree on is that they want to make the most money. They often can't even agree on how to go about that.
So, the board won't fire him because the shareholders won't force it. The shareholders won't force it because they want the most money, and musk as CEO seems to be the best path, or at least not a problematic one.
As for how that can be, it gets into how absurd Tesla stock is in the first place. There was a period where Tesla's market cap (total value of all shares) was higher than the entire rest of the auto industry combined. This was despite having no feasible path towards that level of production, and even growth in general wasn't looking too hot.
There are legal hurdles to raising rates based on this data. The simple and obvious solution is to set the starting price as the worst-case driver scenario, then discount down from that.
It's the exact same thing, but worded different.