First, unless you have a very poor imagination almost nothing turns out to be as good as you imagine it will be when you first think of it. I remember a line from an old move called Morgan: "Reality never quite lives up to my best fantasies."
Second, it takes lots of trial and error to get to the point where you can even get close. That's where the drunken baby comes in. It's not actualliy drunken but when it's learning to walk it sure seems like it. It staggers, falls over, gets up, takes a few more steps, falls over again, and on and on. At first it has to hold on to something, then it takes a few independent steps, and eventually it's racing around the house.
The baby doesn't think, "Hmm, I've fallen over a dozen times, I guess I'm no good at this walking thing. I'll just stick to crawling." It keeps going until it has mastered walking.
Of course this is a strong instinct, not a conscious decision. I think the desire to express ourselves is also a strong instinct and to learn to do it well we have to fall over a lot and get up again and again.
Even when a kid has mastered walking, it still stumbles from time to time. That happens even when it has became an adult (at which point alcohol may indeed play a role).
Even when you are an experienced writer, some projects will not work. You'll feel disappointed in yourself or the world, or both.
Then you'll remember to stand up and keep going.