If you want to get anywhere with it you do. If you don't care, then it's entirely up to you if you proceed or not.
I know the feeling. I was 110k into a sequel and wasn't feeling it anymore. Granted Sci-fi doesn't need any more war stories....it is full of that simple crap. After some time off from writing, I finally found other things to write about instead, which can still be in Sci-fi or contemporary fiction. Sometimes it takes something new and exciting to get the juices flowing. Even a challenge to write something you never thought you could, can be a good way to get some mojo back. Sure not everything you put out will be the 'next big thing', but you learn by looking at where the bad stories went wrong. So, you don't repeat the same missteps on the next one. Good luck, and I hope you find something new to spark your inspiration. Happy Writing.
The first thing that entered my head when I read this, is a question: Have you had any beta readers for your story, or are you just going it alone? Betas (good ones) can be VERY helpful. They may see what's 'wrong' with the story or the way it's written, and can offer suggestions for improvement which you might not have thought of. It sounds to me as if you are just vaguely unhappy with the result—and feel that it doesn't match up to your original vision for it. A fresh pair of eyes on the manuscript might offer a breakthrough that gets you enthusiastic again.
Don't give up just because it didn't quite work out the way you wanted the first time. It happens to all of us. As you do it more often, it will get better, if you put the effort into getting better. If humans gave up after things didn't go so well the first time, none of us would have any children.
I get super depressed every time I finish something. It's not just that I think no one will read it. It is also the fact that when it is finished, and I am done with it, it isn't being cultivated anymore. If that feeling was all their was to it, of course I'd stop writing, but then I just end up feeling like writing again in a day or two, so I do. I think people write because they feel like it. OP: if writing were easy, then everyone would be good and no one would stand out. Lottery tickets are usually only sold to those who endure the longest lol
Then you move on. The day after I finish a book, I'm on to another one. I never take a day off. There are always other books.