Not everyone is going to love your script. How are you going to deal with that?
Dealing with countless no's, closed doors, and people dogging on your script isn't pleasant. I know, I know—it's easy to believe our ideas are plucked from Heaven's most fruitful vines and that everybody and their uncle is going to love it and "get" it and want to throw a million dollars at it, but ya know—it's probably not gonna go down like that.
People are going to dislike your shit. Your friends are going to read about two pages, wince, and promise they're going to finish it later on when really they're going to toss it on the top of their "Leaning Tower of Shit I'm Gonna Deal With Later." Worse yet, you send it off to a producer and they dislike your shit. They close the door on you faster than you can say "Please, for the love of Pete, just read my script!" Even worse, you get hired, think you're a big shot, and get pages and pages and pages of notes about why a room full of executives dislike your shit.
Believe me, I understand that experiencing rejection, criticism, and failure is painful to endure as a screenwriter, but it's absolutely necessary for your survival. If you're having a difficult time with this, let Mark Sanderson (a.k.a. Scriptcat) drop some truth bombs on your ass.
"As long as you're writing, you've got a shot—you've got a chance."
What is the single most devastating thing to a screenwriter's career?
Think about it.
Keep thinking. Ponder it. Really get in there.
If you said something along the lines of failing to get a script optioned or having your script dragged through the mud of creative criticism, you, my dear, are sorely mistaken.
What could be more devastating to your screenwriting career than you not screenwriting? That's when you've removed yourself from the game, from the discourse, from the pool of options, and how do you get to that point? Usually, it comes from years of failure and slammed doors wearing you down until you feel like you're "just not cut out for screenwriting," but guess what. You can choose to take that rejection, criticism, and failure and turn it into information that will help you write better, more successful screenplays. As Sanderson says, this business is not for the thin of skin or huge egos—the machine will eat you up and spit you out—it's for those who are willing to collaborate, learn, and compromise. That tenacity and willingness to give and take will help you become a better screenwriter.
If people dislike your shit, fine! But keep writing your shit. Work on your shit. Nurture your shit. Because eventually, it won't be shit.