A lot of the dying wishes are simple or relaxing hobbies (baking, knotting, fishing ect..). It's like a part of them also continues to live with Chaeyoon when he does it. So it's when he's fishing, he's fishing with that person or the memory of them. But most importantly, I think they did it because they wanted him to live, live a normal and quiet life. They had no guarantee that they could save the world, but maybe they could save this one kid.
My childhood