Some children climb to the top of Mt. Ebott because it's something new to explore.
Some children climb to the top of Mt. Ebott to help the monsters who they've heard in scary old stories are, well, monsters, but monsters are people too, they have minds and faces, and if someone is a person they are worth caring about.
Some children climb to the top of Mt. Ebott because being sealed away isn't enough, they're, well, monsters, and a lot of those other children were never found.
Some children climb to the top of Mt. Ebott because they don't want to be found in time for cryo.
And some children climb to the top of Mt. Ebott because today's randomly sampled location in their square sector on the world's surface is near enough to where they're camping and lands on top of Mt. Ebott, and that kind of child is the kind of child that this story is about.