Because you have to admit there is a level of narcissistic assurance one has to have to be new and think they will be successful in a profession filled to the brim with killers.
FULL DISCLOSURE: To this day I can't read a good screenplay in one sitting without putting it down saying, "I should just quit now."
No shit. They're good, and their work is good. That's why you're reading it.
But it doesn't mean you quit.
The ones that inspired you are mystical teachers beckoning you to what you can be in your own right if you follow your own path. So do that.
FOLLOW YOUR PATH.
I guarantee you none of your favorite writers were as good as they are now when they started, and they've been where you are.
They had to be arrogant enough to walk their journey in the dark alone with distractions and naysayers.
They survived and so will you.
You earn arrogance and self-esteem through challenging work though so work first and all that other stuff you want will soon come.
Keep writing. Keep refining. Be arrogant.
Michael