Originally Posted by
Okipuit
The "gil saving chest" was created as a feature that protects against mistakenly bidding or purchasing an item for too high of a price. For example, if you're going out with the intention to purchase an item that's 300,000 you can withdraw just that amount and have no fear of accidentally purchasing it for 3,000,000.
As for having an interest or reward system for storing your gil, we'd like to avoid scenarios where users would need to gather a large amount of gil in order to make a profit or receive a prize. With that said, there are no plans to implement a rewards/interest system.
Lastly, the "gil savings chest" will only store gil. There are no plans to store other items in here as well.