By now I know three major languages: Go, Python, and Typescript. I know tradeoffs at-a-glance, I deeply understand the syntax and its various forms, the full array of tooling and what they do, and lastly (but maybe most importantly) I can estimate more accurately because I can architect in my head.

I can work in a myriad of other languages. I may be able to do some of the things above in Java or Rust but not nearly to the degree to which I can in languages I know. I think the difference is I'm probably not going to be leading a Java project or producing anything really innovative at a code level.

To me, more important than picking a hammer, is knowing a variety of hammers that are good at certain tasks. I don't focus on Rust or Java as much because, frankly, I can build most things that are pertinent to the constraints of my work environment with those tools and most people I encounter also know them. The other considerable factor I have is that most things I work on can be horizontally scaled so my need for Rust is very niche. With respect to Java, I have a lot of workarounds that are cleanly abstracted enough before I need its dynamism and subsequent mental overhead.