When You Find Out Your Reason

I hear Brooke repeatedly says that whatever we choose to do to make sure we like our reason.

I am a new scholar but few months before I joined I have decided to write my first screenplay.
Being inexperienced and in a hurry to get it written (so I can find an agent), I decided to write a detective story.

For few months I have been developing the story, the characters and even a preliminary outline and all the while I’m thinking to myself:
I don’t even like detective stories, and I’ve seen this a hundred times.

So I hired a screenwriting coach and showed her what I’ve done so far and she told me it’s been seen and done a million times, that it almost feels like I just changed the names of my characters and their professions but it looks exactly like other things she saw.

She then asked me why did I choose to write this and do I have particular love for the genre.

My reason was: I read a few screenplays of detective stories, saw a certain formula and thought I could write it quickly so I can get to see it done and get an agent with it.
She thought it was a poor reason and a very bad way to start my screenwriting career. That it’s desperate, unoriginal and hurried, and therefore not good and will definitely not gain representation.

One of my goals was to complete the screenplay by end of December 31st 2018 and yet now I consider dropping it because I realized my reason was not good.
I feel though I am having a hard time explaining to myself, if I do decide to let go of this project, how I wasted all this time.
Would love your help on that.