Here is the honest truth: stepping from Ruby into systems languages is the biggest mental shift you will make as a programmer. It is not like learning a new framework or even a new paradigm within dynamic languages. It is learning to think about things Ruby has hidden from you for years -- where memory lives, how long it lives, and who is responsible for cleaning it up.
The culture shock is real. In Ruby, you think about objects and messages. In Go, you think about types and values. In Rust, you think about ownership and lifetimes. In Zig, you think about bytes and allocators. Each one strips away a layer of abstraction you did not know you were standing on.
Now, the uncomfortable question: do you need all three? Honestly, no. If this is about career utility, Go alone gets you 90% of the value. Go is where the jobs are, where the infrastructure is, where a Rails developer can make a lateral move without a two-year ramp. Rust is beautiful but the job market is niche -- mostly crypto, embedded, and Mozilla-adjacent projects. Zig is fascinating but it is pre-1.0 and the ecosystem is tiny.
But this curriculum is not just about career utility. It is about understanding. Learning Rust teaches you why garbage collection exists -- because manual memory management is genuinely hard, and ownership is Rust's answer to a problem that has killed software for fifty years. Learning Zig teaches you what C actually does under the hood, without C's landmines. These languages make you a better Ruby developer because you finally understand the cost of every each, every block, every object allocation.
The real payoff is not writing production Rust. It is reading a flame graph of your Rails app and actually understanding what the garbage collector is doing and why. It is looking at a slow endpoint and knowing whether the problem is algorithmic or mechanical. That is what systems thinking gives you.
Go first. Rust if you catch the bug. Zig if you want to go deep. That is my honest recommendation.