>Give them meaningful objectives
There
The thing I like about Space X is their balance that was referred to earlier in these comments. Risk vs. profitability vs. engineering cool things. They also take the position of mitigating risk through USING their engineering and technology skills. At the heart of it, using repurposed thrusters from oil rigs to make a seafaring landing platform isn't "difficult" per se... but there certainly is ingenuity there. Not only did they make something cool with their engineering skills and ideas, but they made something that makes their development of "spaceships" safer.
I'd love to work for spacex or tesla. I don't care how much they'd pay. I'd just love to work on projects similar to what they've already done. Heck if I could otherwise feed myself i'd just happily work for free.
It doesn't mean he's doing the bulk of the work, but he is playing a role that is irreplaceable, and it may not matter so much who the other people are so long as they are competent. It seems he is able to achieve similar results each time.