Rich people are into it because they have the budget to make science fiction a reality, that's a no brainer.
How did you come to the conclusion that "transhumanism" is a fetish of the super rich? You're endorsing transhumanism simply by publishing on the internet and accessing the technology that you are.
Far before rich people were into it, the ideas were dreamed of by writers and futurists, artists and some scientists.
Silicon Valley was "seeded" by Tim Leary, Robert Anton Wilson, Bucky Fuller, Allen Ginsburg, the "Hippies who stole Physics" to name a few. this happened via underground literature. Their ideas were about what is possible in the future.
Rich people, historically speaking, fund waves of innovation, that started before the pyramids of Egypt.
Why does it appear to me that you're framing this as some sort of weird perversion? "These are the people?!?!?...(your quote)".
The dark impact on Silicon Valley are not the inspirations of the designers, but the influence of Wall Street. Designers, writers, creative types especially, can be weird and eccentric, and sometimes your criticisms read a bit too socially prudish to be meaningful to the reader.
Of course the balance is possible, thats what the work of Leary and RAW and team was all about, humanizing the technology. We are not there, yet.