They've been exposed to the outside world, up close and personal. They've had that fear planted in them. And they've endured it. Overcome it. Each has grown from that experience... and forgotten how to hesitate.
Heroes and villains both thrive on violence, but we're still categorized. "You're good." "You're evil." That's how it is!! Symbol of peace? Hah!! In the end you're just a tool for violence, made to keep us down! And violence only breeds more violence.