Are you really asking why someone should bother learning assembly language?
Even if you never use it for a real program, learning it will give you a better understanding of how computers work.
Meanwhile, are you familiar with writing subroutines? If so, all of the subroutines that you have written were probably in the same high-level language that you've been learning, but a high-level language can call a subroutine written in a low-level language.
So, you don't have to make a choice to write 100% of a program in the low-level language.
However, most programmer don't have a reason to actually write such code because if there is a common need then a library of subroutines can often be purchased.
Of course, *SOME* people *LIKE* the challenge of writing low-level code.
Also, I have modified assembly language programs written by someone else, so I didn't write the whole program, but only the part that needed changing.