So . . . you think giving up is going to solve that problem? I didn't start seeing real improvement in my art until I was 18, and I had been drawing for 14 years growing up. If you really want to learn how to draw, your learning shouldn't stop at 4 years of classes. Start doing your own part to improve, whether it's drawing in a park or spending an hour or two drawing each day. If you expected improvement from classes alone, then your expectations are set too high (especially considering there's a huge difference between learning how to draw vs. attending classes to teach you how to draw. The former, you learn, the latter, you follow along, and maybe learn some tricks, but unless you're willing to step outside your comfort zone and try to apply the things they teach you, you're not gonna get anywhere).
At the end of the day, no one's opinions in this thread matters, because this shouldn't be about what other people think. If you want to keep working on your comic, then go ahead. But if you've lost the energy to do it and just don't care about it anymore, you shouldn't be trying to look for validation to do something you already know is dead to you, because then you're doing it for everyone else and not for yourself.
I spent 10 years coming up with Time Gate, and about 6 years writing it as a novel series that I never found success with. And I never did find success with Time Gate until I started doing it as a comic. I'm still writing it, trying to figure out what works, what doesn't, etc. and it's gonna be many years before the manga series is finished (it's gonna take me up to 3-6 years just to finish Time Gate: Reaper alone).
It's only wasted if you consider it wasted. In which case, again, if this project is already dead to you, then there's no point in seeking the validation of strangers to make you feel better, because it won't in the long term. This sort of stuff doesn't happen overnight, after all.
I get that I'm coming across as a bit harsh, but I'm mostly just trying to explain the actual reality of the situation and not spoonfeed you with false encouragement and empty promises. Would you rather hear people cheer you on for a project you no longer have love for, and waste even more time on it, or figure out what you want to do yourself and maybe save yourself more years of unhappiness and un-fulfillment? (and that's if you choose to keep going but want to give up; if you want to keep going, you need to fuel that motivation yourself, not from the requested motivation of others who won't be affected no matter which option you choose).
EDIT: As others have mentioned, what's keeping you from writing it as a novel? To me, it doesn't seem like there's much point in forcing yourself to learn how to do something new and even paying money out of your pocket to get someone else to do it for you just for the sake of making it a comic when you could just as easily make it a novel, especially considering you already feel confident in yourself as a writer and already feel capable enough of doing it that way. Maybe even to start, and then while you're working on that, keep studying art and such if you want to improve your art skills, and do it as a comic later when you feel you've improved enough to do so (if you just really want it to be a comic for personal reasons).