Exactly, the fun part is when the code works and does what you wanted it to do. Writing code itself is not fun. People forget this because they get small wins / dopamine hits along the way, a clever function, an elegant few lines of code, a bug fix, but the majority of that time coding is just a grind until the end where you get the big dopamine hit.

Fun is not measured objectively. Different people find different things fun. I enjoy writing code very much (in addition to solving big problems; one can enjoy both).