though Julia is not a self-host language, in practice, especially in scientific research, a pitch I often give is: all the parts you would ever care about is in Julia and you can read, understand, and even tweak at will. I’m referring to the fact that base and stdlib are in Julia and packages are more often pure Julia (at least for the part that does heavy lifting).
Unlike, for example, Numpy, where one hits C code super quickly once start digging (even function as simple as mean is written in C).