I have never, nor will ever believe that you only get one chance. Life is not black or white, but rather, several shades or colour. People make mistakes all the time but have the power to redeem themselves. There are stories everyday of people who were near death and survived. With the right intervention, people can be given the opportunity to try again and learn from their mistakes.
I believe that everyone deserves a chance to correct his/her wrongs. I believe in this because I consider mercy as one of the core virtues our civilisation should strive to. Imagine if we were to live in a world where every mistake, great or small, would be harshly punished. That world sounds a lot like fascist utopia. Second chances, and mercy by extension, are a sign of belief in people, belief that even though they make mistakes, they can still pursue the dream of making themselves better.
Yes, I believe in second chances because there are countless stories of people on the verge of death who have gone on to do something great with their lives. Everyone deserves a second chance, but not everyone gets them. Those who survive something like a heroin overdose should live their lives to the fullest.
Imagine if you went into a place where nobody knew who you were or what you did in the past. The only things that they could gauge you are on what you do after you meet them. In that way, we all get second chances all the time, because we're constantly meeting new people who don't know about our past.