[mveldthuis]

Except that you don't. If Dropbox screws up, and the service deems your files gone, the clients delete their copies too. At that point, you have to hope that somewhere, at Dropbox, the file still exists, or that some client was disconnected from the network, and still has your files.

It protects you against the unavailability of Dropbox. Not against screwups on their side.

[Dylan16807]

Dropbox does keep a cache of recent file versions. So a server-side screwup won't entirely ruin your local files. Still, you're right that more backups are needed to avoid a single failure point.