Because, to this day, Dropbox is the only cloud storage service that is capable of syncing only the part of a file that was modified. If you have ISOs, zips etc

Because, to this day, Dropbox is the only cloud storage service that is capable of syncing only the part of a file that was modified. If you have ISOs, zips etc, GDrive will re-upload the entire file while Dropbox will only upload the changed parts. This alone is why I keep using Dropbox.