Growing in absolute numbers doesn't mean growing the market share, and even a growing market share is not necessarily sufficiently fast growth to become a safe bet. All languages that ended up becoming very popular grew their market share much faster than Rust does. Being an old language with some real market share is obviously better than being an old language with negligible market share, but being an old language with real, but small, market share is not exactly a sign of confidence.

It's true that the total market share for low level languages (C + C++ + Rust + Zig + others) continues declining, as it has for a couple of decades now (that may change if coding agents start writing everything in C [1] but it's not happening yet), but that's all the more reason to find some "safe bet" within that diminishing total market. Rust's modest success is enough for some, but clearly not enough for many others to be seen as a safe bet.

[1]: https://stephenramsay.net/posts/vibe-coding.html