"rejection is an inherent part of writing, not just on Medium, but everywhere."
I'm a writing coach and editor who helps Medium writers craft boost-able stories and I'm also a pro writer who has spent decades writing for everyone from the New York Times to the Funny Times and this is something I tell the writers I work with all the time.
Every story that is worthy of a boost doesn't get boosted.
But a story that isn't worthy of a boost won't get boosted.
All you can do is write a great story and hope for the best.