Safe modern c++ is poorly understood compared to the decades of experience and knowledge corpus around old practices. The unsafe ways are still easily accessible and widely used, taught, and understood. C++ also is laden with complexity and idiomatic styles, immense foot cannons, etc.

Rust is fairly explicit with what’s unsafe (ie unsafe) and safety is default. It’s also generally a simpler language overall with less accretion of backwards compatibility. There aren’t decades of bad habits still usable in rust. It’s got modern sugar, first class functional constructs, and it’s generally cooler in the way metal was cooler than big band was in 1988.