Going back *several posts* to Anthony's (and many others who have written in on this thread): I agree... there's a huge problem with a certain subsection of new writers who have an idea, write it - and then believe that they'll somehow manage to get "discovered" and sell their work for $100K+ dollars. Maybe even a million!  (Yay...)

Which isn't to say that some scripts aren't worth that.  Even by newbies (though the odds are very much against an absolutely new writer turning out a first draft that's so attention grabbing that it could reach those heights... at least without a very long, painful slog through honing and polishing one's craft.)  Point being, screenwriting is far from being a lottery - even if you're a top notch writer.  As Pia mentioned, even if you DO break through, there are quite a huge number of writers that get one thing produced and.... that's it.  (Which is why scripts SHOULD sell for huge amounts, when there's a major studio involved that can afford to do so.  Because - there's no guarantee that there'll be another any time soon, if ever.  And who's going to pay Con Ed and the mortgage, huh?)

On the flip side of this; those writers who are born to it, do it also for the pure pleasure.  Yes, it'd be so much more peachy keen to see a script produced.  But the very act of writing and creating worlds is pretty wonderful itself.  Anyone who is made for screenwriting will do it - whether or not the script makes it to the silver screen.  

But never, ever hold your breath.  Writers have to make sure they have Plan B, C, and D in place. And keep going - whether or not that big break ever comes.  (And don't put your future on hold waiting for it, either.)  Just enjoy the hell out of the process. Writing's a habit that infects one's blood, soul and brain...