Could you elaborate on how Katja's idea in the OB post might be used here? To me, it seems like it supports the OP (quite nicely, actually). In particular, Elon Musk shows that Tony-Stark-ness (as you've correctly defined it) is pretty darn visible. If there were more Tony Stark's out there, I'm now more likely to expect expect that I would have heard about them in the same way I've heard about Musk. This increases my confidence that there are not many Tony Starks compared to my pre-Musk assessment.
And then, of course, the question is: with so many billionaires out there, why?
"Could you elaborate on how Katja's idea in the OB post might be used here?"
Exactly in the way you describe. I was indeed using it to support the OP and not myself: "I'm not sure which of us is right, quite possibly the author and not me - LINK".
I don't know. It was one of those comments that started as one thing and by the end I'd basically persuaded myself of quite the opposite. The turning point I think was getting used to the idea of <1500 worldwide billionaires. For some reason I thought there were a lot more than that. I suppose I imagined them all hanging out together, puffing on cigars and saying things like "that Elon eh - what happened to just saving the planet without being on the front page of Hacker News every day?".
And then, of course, the question is: with so many billionaires out there, why?