Nopony knows about the asylum. It doesn't exist, even though they purposefully avoid the grounds it doesn't exist on. The walls of it are invisible to them, along with its inhabitants.

And inside the asylum they stay, dictated by the head nurse. The Purple One.

Some things are simply best left unseen. (inspired by Ken Kesey's One Flew Over the Cuckoo's Nest, but not just a pony version of it)