I literally laughed out loud at this. Obviously greatness is subjective, but you are really reaching if you think someone saving a billion lives isn't 'on the same level' as Elon Musk who has yet to go to the moon (although I'm sure he will), who has yet to make a profitable car company (this one I'm not so sure about), who has yet to change the energy infrastructure of the world (he's chipping away at this one steadily).
The important thing about history is it's written after the fact. If Elon Musk died today he would be remembered for his work at PayPal and starting several ambitious companies before they achieved financial success. I'd wager that if he died today all of his companies would fail and he would be remembered for trying to do too much and working himself to death before he achieved his goals. He could very well end up as a Greek tragedy.
The important thing about history is it's written after the fact. If Elon Musk died today he would be remembered for his work at PayPal and starting several ambitious companies before they achieved financial success. I'd wager that if he died today all of his companies would fail and he would be remembered for trying to do too much and working himself to death before he achieved his goals. He could very well end up as a Greek tragedy.