- Stakes create empathy. Knowing the main character has something to lose helps the reader care.
- Stakes help the reader invest in the story. When you shine the reader spotlight on "If Main Character doesn't do BLANK, then DOOM will happen," the suspense intensifies by a factor of 57% (or thereabouts).
- Stakes are a big part of what keep a reader reading. They're the match that lights the "What's going to happen?!" fire.
How do you figure out what the stakes of YOUR story are? Try framing it as a "What if?" What happens if your Main Character fails? What if they don't save the world? What if they don't let themselves fall in love? What if the bus driver never solves the mystery of why he wakes up with a new tattoo every morning?
That feeling of unease you're feeling (assuming you let me boss you around, your imagination is functional, and you have a heart)? That's what you're shooting for in your stakes-based pitches and in your query. Make the reader uncomfortable. Introduce them to your amazing, unique, memorable main character, show them what that character wants more than anything, then make them sick with worry over the potential consequences.
Not all stories have happy endings. Make your reader terrified that yours might be one of them.
The best writers, and the best stories, are equal parts empathy and sadism. Make them care. Then make them HURT for it.