It's quite the opposite: the larger a C/C++ project gets, the more problem you are starting to have with safety. Securing and modifying millions of lines of C/C++ code (especially if it's multi-threaded) is a nightmare, and actually impossible, where people are afraid to refactor old code because all the ownership uncertanities.

Rust changes a global ownership tracking problem to a local one.

You'd pretty much never make the move from Java -> C++ because of the lack of safety. But you may want to do it because of the other non-safety features.

That is where Rust is interesting and competitive. It's the performance and memory footprint of C++ with the memory safety of Java.

I think it's becoming increasingly clear that "addressing the problem" in C and C++ means fixing all the memory safety issues you know about. Sqlite is the posterchild of careful testing in a C codebase, and they had a serious CVE last year. Realistically, the vast majority of C and C++ projects have more bugs than that, even if they're staffed by experts who take security seriously.

But I agree with you about the cost-benefit analysis. It's not very often that security issues destroy an entire company, and trying to rewrite a large codebase might be existentially riskier more often than not.