I have 52 manuscripts in my Just Writing dropbox folder. Some are complete, some have a couple of filled-in scenes and then basically a synopsis to remind me how I meant the story to go. None of them are sellable or even readable.
Not sure about all authors, but I get ideas a lot. I'll think, whoa, I'd really like to read a paranormal romance where the heroine hooks up with a not-as-evil-as-he-seems anti-Christ sort of dude. So I go off and write 60k (so, so dodgy) words because I'm so into the idea... and then I stumble across a book on a shelf somewhere that has already dealt with the topic. Brilliantly. Perfectly. (Thank you, Darynda Jones. Your version is the one the world needed.)
So anyway, my answer to this week's question -- do you ever abandon a project, and if so why? -- is yes, and because sharing the story isn't necessary. It was enough to have written it to settle my own brain.
See, thing is, not every idea that bubbles up in a writer's brain is going to work for actual readers. And not every writer is capable of writing every idea they have.
It's okay to put that first manuscript in a drawer. It's okay to say, you know what, there just isn't room in the market for another Harry Potter clone. (Inner voice says, "Yeah, but ours is with fresh-out-of-high-school new adults learning magic as a profession and how to adult and ..." and I say, "Shut up, inner voice. Seriously, just shut up.") It's okay to realize you've grown as a writer since you started working on that space opera that, let's be honest, was just a Deep Space Nine fanfic with substituted names.
It's okay to write those for-pleasure idea bursts. It's even okay to love them.
And it's also okay to let them go.