People aren't code. Sometimes teams get a culture that you want to change and it's generally extremely difficult, if not impossible to change team cultures incrementally because a) they always hire people that have the same culture as them, b) they're used to the existing culture, and c) people hate being told they have to change.
So I think it may not be as crazy as you make out. On the other hand were they really underperforming? Isn't Tesla's charging network still world leading?
If there is a bad culture then work to fix it. If there are underperforming employees then root them out. Like you said, it's not like 500 totally incompetent people built out the largest and most powerful EV charging infrastructure on the planet in a matter of a decade.
How much of that is the result of the individuals on the team themselves and how much is that the result of the organizational pressures, constraints, and expectations they're working under?
I suspect that just replacing the individual people would result in more or less the same unhealthy culture unless you also took steps to change the rest of the organizational context.
So I think it may not be as crazy as you make out. On the other hand were they really underperforming? Isn't Tesla's charging network still world leading?