What were these "things" that Musk did, and in what way do they constitute proof of "greatness"?
I don't think you really know. You gesture vaguely at re-usable rockets, as if this isn't something that engineers haven't been trying to develop since the 1940s, as if the fact that the most recent developments were completed by engineers under his employ confers on him some sort of "greatness" simply because he owned the single largest share of stock in the company.
You describe a "vast technological empire", but what does it consist of? A rocketry company that subsists on public subsidies. An automotive company that produces a statistically insignificant number of high-end vehicles; that is, in effect, a luxury goods company. A tunnelling company that has completed one pretty mundane civil engineering project in Nevada. A scattering of tech start-ups that are yet to produce any technology of note. This is greatness? This is the pivot upon which human history turns?
But Musk tells you that he is a hero. He tells you that he is going to save the world, indeed, create new worlds. Capitalism has overthrown religion, has dissolved all myth, without removing the historical conditions that produce the need for religion and for myth. Is it any surprise that we should find new demigods?