I know some paramedics that reached this point.

One I'll call John. He was a fantastic medic. Calm and reassuring in the toughest situations, and he was a great teacher of new EMTs. He had seen everything. Farming accidents (they're terrible), DRTs, MVAs, MCIs, child abuse. The works. Handled it all professionally.

One day John and his partner get this nothing call. Kid fell off his bike and scraped his knee. John's partner puts a bandaid on the kid, looks around and John is gone. They find John sitting on a curb a block away bawling his eyes out. That kid with the skinned knee was John's breaking point. He was done.