This line of thought always comes across as "ego defending rationalization" to me. That is, we don't like to believe that someone who is such an ass clown can be so successful, so we just chalk it up to his family's wealth or luck or something.
But it's clear to me from Musk's communications that:
1. He is extremely intelligent, at least in his ability to understand topics across a wide range of areas (business, technical, finance).
2. He is extremely driven. He could have easily put his feet up after PayPal but he chose to get involved in immensely difficult, grand projects.
3. He works extremely hard (at least when he isn't tweet trolling). I don't think anyone questions his long work hours and sleeping at the office during the Model 3 production ramp up.
4. At least until recently, he was able to get other extremely smart and driven people to follow his lead.
I guess it's really number 4 that seems like the biggest change in the past couple years in my opinion. I mean, I've got to believe a lot of smart people at Tesla and SpaceX are looking on thinking "WTF is Musk on??"