Vault vs. Custom Solutions
Many organizations resort to custom solutions for storing secrets, whether that be Dropbox, encrypted disk images, encrypted SQL columns, etc.
These systems require time and resources to build and maintain. Storing secrets is also an incredibly important piece of infrastructure that must be done correctly. This increases the pressure to maintain the internal systems.
Vault is designed for secret storage. It provides a simple interface on top of a strong security model to meet your secret storage needs.
Furthermore, Vault is an open source tool. This means that the tool is as good as the entire community working together to improve it. This isn't just features and bug fixes, but finding potential security holes. Additionally, since it is open source, your own security teams can review and contribute to Vault and verify it meets your standards for security.