There are a thousand things about the past, I think to myself, that I would change if I could. But I am mistaken, thinking that then something better might happen instead. There is just no way to know what might have happened instead. Hopefully something good, possibly something bad.
Some would go back and kill Hitler. Why? There is no guarantee that killing Hitler would be better, because we cannot possibly know. There is every possibility that someone even worse than Hitler might appear as a direct consequence of killing Hitler. What then? You just cannot know.
Changing the past makes absolutely no sense, because we cannot know what we are changing the future into. We cannot be so naive as to assume that anything would’ve been better. It could be worse.
Perhaps it doesn’t even matter if we alter the past. Suppose the universe is in some sort of equilibrium. It would then counter any changes we made so that the future stayed the same. It’s not unthinkable. Nature is full of different equilibria. Some would call it destiny. I wouldn’t. Destiny is meaningful and final. There is no meaning, and I see no reason as to why existence should ever end.
If there indeed is an equilibrium, then traveling forwards and changing the future should change the past.
Not wanting to change the past, no matter how horrible, is a step towards accepting it. With that comes maturity and growth. When something bad happens, part of the pain is the thinking that it would have been better not having happened. If one can deeply understand that this thinking is false, it might not hurt so much.