After reading, I'd say your base question/thesis is: "Why on Earth aren’t there more billionaires doing really cool sci-fi sh!#?". You go on to give plenty of examples (FYI--some of these are already being done such as self-driving cars and flexible displays) but all of them, to truly build, would require a solid understanding of mathematics/physics/some type of engineering right? Not every billionaire has that knowledge. Elon Musk does--I believe he has a degree in physics from Penn and dropped out from the PhD program at Stanford. This knowledge simple does not exist among the majority of billionaires. And exactly because of this lack of knowledge, I don't think billionaires CAN actually do 'really cool sci=f sh!#'.
When you think of a crazy idea, out of the first few questions that come to your mind, one of them is probably, "Is this idea feasible?" To Musk, the idea of Tesla and SpaceX were both feasible, BECAUSE he had the necessary base knowledge in those areas to realize that with money, these visions could become realities. I like to think many people, other billionaires included, have had the idea of cool battery charged vehicles but without the ability to realize it is possible (aka the base knowledge), they stopped at that. Good or bad, this is most likely the reality of it.
All of that being said, I would like to see billionaires do what J.P. Morgan and George Westinghouse did for Thomas Edison and Nikola Tesla, respectively--and that is to find and fund geniuses with these revolutionary, futuristic, 'really cool sci-fi sh!#' ideas. If more billionaires sought out to find scientists/engineers working on 'the next big thing', I imagine more would happen and newer, more fascinating, industries would be formed.
My plea: If you're a billionaire who appreciates what people like Elon Musk has done/is doing but don't have the skills to do so yourself, go find more people like him (in the sense that they have crazy futuristic ideas) and help them to help the world.