They think the programs they write are defect free, because muh buffer overflows and automatic memory management, but little do they know about things like ensuring numerical stability, floating-point error, and so on, etc. They also tend to ignore the fact that the languages Rust is competing against have static analyzers which detect many of the security issues they purport to solve with their language. In critical systems development, we use things like SEI Cert C and Misra C, with analyzers that ensure compliance. For stuff that's even more critical than the average shit consumers end up using, we use formally verified software, and the industry as a whole is moving towards this.
Furthermore, Rust shills have gamed online communities and have invented a larger than reality presence, artificially inflating the language's perceived popularity. They also constantly F5 in their web browser on software bug for In all actual polls with hard numbers, Rust doesn't even show up in the charts. Take TIOBE or the recent Redmonk Language Poll for 2017. Where's Rust? It's a fucking footnote.
Rust has no utility in the real world. People and companies who do real work are avoiding it like the plague for the same reasons I avoid it. Quite frankly, we're getting sick of Rust. Rust is only real in the minds of Rust sycophants. I almost feel sorry for all of the university/college students who are falling for the Rust meme. But in the end, it's only going to improve job security for those of us with real skills outside of Rust.