If Jobs hadn't of gone back to Apple in '97 after being fired in '85, they wouldn't be here today. Jobs was their last hope after Sculley made them mediocre. Apple was down to relying on a 150m investment from Microsoft in the late 90s (Aug 1997), that they probably only got because of Jobs [1]. I'd also argue everything that Jobs had created at NeXTSTEP became Apple and saved them [2]. The technology made it all the way into iPhone, you can see it in their libs still in Objective-C with the NS prefix [2]. Interestingly Jobs built successes in NeXTSTEP and Pixar while he was away from Apple for a decade, just like Musk has other companies.
It could be argued Ballmer almost killed Microsoft, but Bill Gates has had influence in the company all along on the board up until February 4, 2014 as the chairman of Microsoft. Microsoft returned to developer/engineering focused with Satya Nadella was made CEO in February 2014 after the marketing/bizdev focused Ballmer era that nearly made them irrelevant, and Nadella has turned it around entirely back to developer roots.
Tesla is an engineer first, I see that as way more beneficial than some operations or lifetime MBA / C-level executive running it, it will take the life right out of Tesla just like Baller at Microsoft or Sculley at Apple.
[1] https://www.cnbc.com/2017/08/29/steve-jobs-and-bill-gates-wh...