Working (successfully) on two problems that no one else dared to. His two big current companies (Tesla and SpaceX) have significantly changed the dynamics in those two industries. At this stage, the change of the entire car industry to electric cars is inevitable, thanks to the work of Tesla.
If Tesla dies because Elon has lost it in the last couple of years, I wouldn't care a bit. The industry has changed for the good, and even without Tesla we will see the paradigm shift. Also, regardless of what happens from now on, Elon Musk has cemented his status as one of the greatest entrepreneurs of his time.
Now, that he is a narcissist dickhead, that is nothing new, and signs were there all the time, especially after the 'pedo' comments. Of course, that does not make his achievements in those two companies (and others like PayPal) lesser. The likes of Pearson and Fisher were total racists (and massive supporters of eugenics), but essentially created the field of statistics. Schrodinger was a pedophile but also one of the greatest physicists ever. And Elon Musk * is a narcissist dickhead with some very bizarre, if not downright evil views, but also a great entrepreneur. Bad people can do good works that advance the civilization **.
* Steve Jobs was also a pretty bad guy, and in his first 2 decades of impact, Bill Gates was pretty bad too.
** Before I get attacked, I am not comparing him with those guys. He is an entrepreneur with some good technical basis, more similar to the likes of Gates or Page/Brin (although they were technically far stronger). Or if you want to go back in time, comparable to the likes of Carnegie or Rockefeller. Many compare him to Edison but that is stupid considering that Edison was a great scientist in addition to a great entrepreneur.