I'm not a Rust developer, but I must admit I'm kinda surprised by this statement. Let me do my own research.
https://www.stephendiehl.com/posts/crypto.html
Looking for Rust jobs on LinkedIn used to yield mostly postings in crypto. That may not be the case anymore with the downturn, my guess is that there are just fewer rust jobs now that the crypto ones are gone.
I think the reason is simply that crypto companies didn't have the clout or stability of big tech and also the sector has a poor reputation amongst engineers so they pick hip languages to compensate. Like "Yes I know, working in crypto is terrible but did you think about how you could write Rust everyday instead of Java??"
(I'm hoping to put a tiny dent in that by growing our non-crypto Rust team over the next couple of years. And I won't hold anyone's former means of putting bread on the table against them ;))
I know a handful of rust developers who refuse to work on anything that touches a blockchain, and they regularly express frustration that the majority of rust jobs they see advertised are in that space.
If you are a Rust developer, you pretty much need to do blockchain stuff, as most of the Rust jobs are related to that. And so on.