1. manage the cost. I fund my project out of my pocket. knowing how expensive AWS could be (through my day job), I'd keep my code efficient.
2. yes, familiarity.
Cool to know. Do you use any framework for the backend? And if you don't mind what's the project? I am thinking about using Rust for one of my projects but I am still unsure if I should use it instead of something like NodeJs or Python.
Why? Is that simply because you are more familiar with the language or does the project actually require the raw power of Cpp?