Its not so much that the skills themselves are in demand, its the enormous experience that someone who can command that kind of fee has. The skill set you're talking about can be learned probably in a year or two of 8-5, M-F self-guided learning from Udemy / Coursera / YouTube, but its the experience of using those skills to build something of value that is driving that hourly rate, not so much the skills themselves.

If you feel I'm missing something here, please go into more depth, because I find this all quite fascinating. :)