Elon Musk doesn't seem like the easiest person to work with, but I'm having a hard time thinking of a more accomplished human.
I mean, I guess some people here subscribe to the notion that space travel is imperative for human survival. In that case, you might argue that each step towards it is more valuable than anything else that does not immediately push towards human space travel. Human space travel will save humanity, your piddly vaccine only saves a couple of hundred million people. But that seems a bizarre argument to make (and maybe that's why one really makes it).
Edit: -3 in one hour? Wow. For what it's worth, I made this comment in good faith.
Some thoughts:
1. We all want to live in a world where dreams become reality. I think a lot of us are passionate at this moment in time because we are seeing a dream unfold; not just Elon's, but for everyone that is working to make it a reality.
2. The majority of us are builders, and we are naturally going to be excited about a company that is building, particularly at this level.
3. (Speaking as an American, here)... in the U.S., I think there has been an under-current feeling for the last several years, that could perhaps be paraphrased as, "Where are we heading, as a nation?" I think it is easy for us to lose touch with the pulse of the nation when we are head-down in code at a start-up or elsewhere, but I think this feeling is real. So, this is perhaps at the root of at least some of this passion and excitement. It perhaps affirms, in some way to us, that the collective "We" are still builders.
4. The U.S. does not currently possess the capability of human spaceflight. We are at a point in history that is similar to the human spaceflight gap that existed between the Apollo program and the Space Shuttle program. The success of SpaceX and this mission is another incremental step toward resuming that mission capability.
I think that something that speaks to this is symbolic: an American flag that flew on-board STS-1 was left on the ISS by the crew of STS-135. It is awaiting return to the U.S. by the next American crew that is launched from the U.S.
5. As has been noted already, Elon is one of us. He is a builder. I do not know all of the figures, but I do know that he has put at least $100M dollars of his own money into SpaceX [1]. I think we all understand that these types of efforts are the intense result of many people collaborating together across various organizations, different backgrounds, etc. However, the reality is that these types of efforts require serious vision and investment, and I think, again, to see a builder like Elon achieve this is extremely motivating.
6. Finally, there is something intrinsic inside of all of us that longs to explore; perhaps for many of us, space is the ultimate expression of that longing ("Space, the final frontier."), and we are over-flowing with enthusiasm, wonder and hope at this achievement.