If you watched Doctor Who this weekend, in the UK, you will have seen two Amy Ponds. One 36 years older than the other. The older one has to help rescue her younger self and by doing so, eliminate herself from existence. She didn't want to do it because doing so, would invalidate all she had accomplished and all that she had suffered and learnt.
This is one those impossible moral quandaries that can be discussed eternally, where the damaged profess that they wouldn't change the past, because without it they wouldn't be the person they are today. I agree that if I hadn't got ill I would probably be a different person, but I certainly don't think that person would be someone that I wouldn't want to be.
This weekend I was at a party. It was the 2nd birthday of a very sweet young man. I was surrounded by lively children and their parents. I looked at all these people who I met just before I got ill. They were all impulsive types, who travelled the world and partied hard, and now they are mostly parents who have laid their reckless activities more or less to rest.
Over the last 11 years I watched these wild friends travel and change and grow. I watched them start to take their careers seriously, buy houses and get married. I watched them get pets and then decide to have kids. I watched them mature and change, and they didn't have to endure 10 years of unending pain to do it. Life took care of it. They got older and wiser and had fun along the way. I can look at my friends and see who I would probably be, without all my suffering. I would be different, but not by much, and I wouldn't have had to rattle with drugs to get there.
So when older Amy has to choose between an existence of suffering or to have never lived that life, I would tell her, "save your young self and choose the path of less pain. Just because it's easier, doesn't mean it is wrong".
But in life we don't get to chose which path we take with the benefit of hindsight. We just take each choice as it presents itself. In real life we don't get to see the future consequences of each decision we make. That is the real reason we say we wouldn't change a thing, because it is impossible. I can't wish for something that might have been, because I will never have that. To waste my energy and sanity longing for normality, is not something I would do. So maybe that is what we mean, us damaged and battered people, when we say we wouldn't change a thing. Maybe what we really mean is that we accept we cannot change a thing and that we are just going to take each choice as it appears and face the consequences of those choices.