Did Musk realize it could be done, or did he pay some engineers to realise it could be done?
When companies fail, is it the result of leadership or employees? Companies need great employees and leaders to succeed and without both, they typically fail. Hiring excellent people then motivating them all in the same direction is very difficult. Being such a leader and having access to capital and being willing to risk bankruptcy in very high risk endeavours like this is exceedingly rare.
Musk from the beginning realize to reduce the price, he would have to solve re-usabilitly. So he and the company from the beginning was focused on re-usability. He didn't just say 'this is what we are gone do'. As the company grew and solved initial problems of launch, they slowly figured out the best way to do it. And Musk as CEO was deeply involved from the beginning and and involved in all decisions.
Unfortunately then he stopped taking his dried frog pills and look where he is now...