Is there such a thing as 'too many' ideas?

Agh! My head is constantly exploding with ideas. It is so annoying!
Because of this, I have at least five novels that I'm working on right now, and not a single finished novel. The closest I have to something finished is one extremely lame first draft for a novel that's about the size of a short story.
At night, when I'm lying in bed and should be thinking about how to make the stories I have better, I always end up coming up with new ones instead. And then I get really excited about my new novel ideas and ditch the old ones. RIP.
A few days ago, my older sister told me that I really had to finish at least one novel, so that I had something to show for myself.
I told her "Phooey, I have a first draft," but that wasn't enough for her.
And that's how I learned that, as much as we'd all like it to be, writing can't be all fun and games. We, as writers, have a responsibility to finish what we've already begun. You know why? Because it's doing the world a favor. We won't ever be able to put an unfinished novel out into the world, only a finished one. And so, to make the world a better place, we should do what's right and finish the stories that we began, because the world wants to hear them.