SAN DIEGO — For Esteban Hernandez, living on the streets has been hell. He sometimes thought of giving up. He implored God, “Why aren’t you taking me?” Then he crawled out of his tent Monday morning, pitched on the sidewalk in a B Street tunnel in downtown San Diego, eyes wide at the destruction of a crash that killed three homeless men and injured five others. A crash that just missed him. He thanked God. “No matter how bad it’s been, I’m not ready,” Hernandez said. Hernandez and others gathered Tuesday in the tunnel near San Diego City College where tragedy struck on a cold and rainy morning. They mourned the victims of the crash, a tragedy that intensified the spotlight on homelessness in San Diego.