Since C++ has been around much longer the situation is likely "many C++ experts try Rust, the ones that love it become Rust experts", basically if "preferring Rust" ends up being a soft prerequisite to becoming a Rust expert then those who are experts in both will prefer Rust.
I also think there's a bunch of other factors that lead to a similar bias: general pride in favor of the less mainstream languages, for languages like Rust or Haskell it is probably the case that more of the code in that language is written by "hardcore" people, which means code written in that language is higher quality (but not necessarily through any intrinsic benefit of the language, instead through a selection of who is writing that language).
I'd say that such selection is intrinsic benefit of the language.
First, please be careful with the "experts" broad brush. Not all, and possibly not most, experts will agree on many things. Moreover, actual experts will understand that there are pros and cons that are context dependent. I would hesitate to label as "expert" anybody who categorically prefers one over the other for all cases. That's more like zealotry than expertise.
Second, for my part the biggest hurtles are in two parts. One is that at the boundaries of speed versus provable safety. At some point I don't need and can't afford the cycles added by boundary checks and other Rust guarantees, and the mechanisms provided to mitigate them are as cumbersome as writing (unprovably) safe C++ code (e.g. "const&", "std::move" and other similar constructs) compared with the equivalent Rust. The other is a more a branding problem: gratuitous maligning of C++ is problematic, and projects a sort of arrogance that I find subjectively distasteful.
As with anything, some people who like Rust might get a bit enthusiastic about discussing its benefits compared to other languages, but this is frowned upon and IME usually called out, especially in spaces with some sort of "official" Rust moderation presence.
Anecdotally, Rust developers are the only group I've interacted with that consistently focus on the positives of other languages when discussing different features or concepts, while acknowledging the tradeoffs and clearly outlining the reasoning behind Rust's choice.