I feel this really hard. I have a comic project that was my baby from like... 2007/8 - 2017 and was essentially my motivation to learn how to draw and keep at it. It was outlined with my middle school sensibilities at the forefront (2007 was when I was 12 lol) and was basically just my take on a shonen manga series, like Naruto or etc.
I never sat down and actually drew very much of it out, as I would reboot the drawings for it once a year or every 2 years or so, but I continued designing OCs for it, thinking out plot arcs in the back of my mind, etc. Finally in 2016/2017 I sat down and actually started rewriting the plot because as a college grad, I felt as though the bones were still good (world, basic plot, magic system, etc.) but I knew that a lot of the characters were written super poorly, there were numerous plot holes, etc.
Last November (2017) I actually started redrawing it from Ch 1 again with the intent to start uploading to Tapas/Webtoons/etc. The art and writing were both muuuuuch improved relative to any of the previous versions. However after completing 8 pages I stopped to reevaluate. Although it was a lot better than before, I looked at the big picture and realized that completing the story as designed would be a ridiculous time-sink and for an idea that was simply a patched up middle schooler's story. The story would probably be at least 100 chapters long, which at the pace of ~1 page a week (as I'm an amateur/fledgling comic author) would take, frankly, years. The thing that put it in perspective was that I had been drawing for 2 months and the first big action scene would be like... a year and a half away LOL.
So I decided to shelf the project and tackle some one-shots/shorter projects instead. I'm not abandoning the idea/work completely, in fact I'd very much like to revisit it someday. BUT I'm going to see how I can grow as an author, get some completed works out, and see if I can find a way to do the project that makes sense, even if that's just writing a new story with those characters/world.
tl;dr - Just within the last year or so I temporarily abandoned a story I've been conceptualizing for ~10 years for the same reason of out growing it and realized that by not branching out, I was kind of shackling myself to a story that would almost certainly not be my best work.