The Astral vault had its humble beginnings. It was once a simple brick house, but upon the appearance of the The-Great-Egg the house was quickly repurposed into a vault.
Many souls wished to deposit their extremely potent vibe conduits inside the vault for safe keeping. What we know of the vault comes from its rediscovery. Thanks to that we now have access to the vibe conduits that have spilled from the Astral Vault. Based on the documents recovered we have learned that the Vaults was simply meant, not as a bank for individuals, but as a community pool used to benefit the age.