When people grow up, why do they like to miss their childhood?

When I was bored, I remembered my childhood life, the feeling of being far and near. When I recall, I feel that I was observing my life, and I don't remember much bit by bit. Sometimes I feel sorry for myself and my family, and occasionally I recall the concept of ten years. I found that some people have really known each other for so long and miss them very much, but when I think about it carefully, I haven't seen them for many years and have become strangers instead. I only met that person many years ago and miss that person very much. Besides, I think it would be nice if I could go back to that time now. I can handle more things that I didn't handle well, do a lot of things that I shouldn't do and eat a lot. I didn't feel bitter at that time, but in retrospect, it is a bit contradictory and not contradictory. Life always gives me an unreal feeling.