Development can sometimes be a harsh business. Writing a screenplay is a lot like being a parent. At some point you send your child out into the world where other people participate in his life and development. Inevitably, you will not always like the direction your child goes, but the only way to avoid that is to chain the kid to the bed. It may take a village to raise a child, but it takes an army to make a movie.
Movie making is inherently collaborative.
If you are talented and lucky enough to find somebody who wants to transform your script into a movie, then your script is going to change. That's not a bad thing. Successful Hollywood people are smart storytelling professionals. They want to help you to make your script better. Perfectionists write novels.