It was always a problem of mine. I've got many more unfinished scraps of words, partial character profiles and incomplete plots littering my hard drives than entire stories. I think the first reason for that is my interest in any particular thing tends to disappear pretty quickly. A new idea has a flash to it, a veneer that convinces you of its quality and the thorough joy you'll achieve in your pursuit of it. I've gotten distracted from serious pursuits by new ideas. It's probably a lot like what motivates people to cheat on their spouses. It's a serious problem when a new idea pops in while you're trying to finish work on your previous idea. They say the grass is always greener on the other side. Well trying to give an old idea justice when a new one's inviting you to hop the fence feels a lot like ripping out clumps of dirt in the yard, looking for grass underground while your neighbor's inviting you to check out his brand new astroturf. As absurd as that run-on sentence might seem, it encapsulates the motivation behind hopping the fence. I've hopped that fence too many times to count; I'm a sucker for some astroturf. Turns out the stuff's fake. Looks good on the surface, but it doesn't have any substance. That's what an idea is; a cheap reflection of a finished product. Everyone's got an idea, and everyone's so focused on asking brilliant minds where they get all their great ideas. They miss the point entirely though; the idea's nowhere near as important as what you do with it.
For your idea to have any value, you have to work on it. To give an idea what it's worth, you have to finish working on it. I've been realizing the importance of finishing things in the past few days. I set out this challenge for myself: write 2000 words a day. I've been mostly successful, missing one or two days a week since I've started (though a side effect has been a sneaking irregularity in the drafting of blog posts). It amounts to quite a bit of writing time, especially when you count in all the distractions that try to pull you away (YouTube and Facebook being the biggest culprits in my case). A good chunk of this time was eaten up by a nearly 20,000-word monstrosity, an attempt at a cyberpunk story. I wasn't even halfway through it when I realized it was bad. Part of it was the "I'm a horrible writer and shouldn't be doing this" kind of bad, but, more importantly, was the sneaking feeling of "This story doesn't really have a plot and these characters are boring." I finished that story earlier today. I don't think I'll be reading it, or doing much of anything with it. However, from finishing it, I've learned the importance of finishing what you start. A bad story carries at least one lesson with it (like "figure out your plot at least a bit before you start writing"), and it builds experience. An incomplete story only teaches you one thing: you didn't have the guts to finish it. It takes guts to power through a terrible story as you're writing it. It takes guts to admit to yourself the story you're creating is no good.
Those 2000 daily words could have been put towards other stories, towards things that may even have been good. But if I hadn't finished this stupid 20,000-word attempt, would I have finished any of them? It felt like I was wasting words while I wrote them, but it turns out there was a purpose to each one.