Why did Anakin become a Force ghost?

Why did Anakin become a Force ghost? As Anakin was the Chosen One, he was unusually strong with the Force. It is possible that Anakin’s redemption and sacrifice were enough for him to become a Force ghost. However, Qui-Gon Jinn provided an example of a Jedi completing their training even after death.

As Anakin was the Chosen One, he was unusually strong with the Force. It is possible that Anakin’s redemption and sacrifice were enough for him to become a Force ghost. However, Qui-Gon Jinn provided an example of a Jedi completing their training even after death.