This is a hypothetical Dropbox situation.
Let's say you're in an accident, serious enough you're not going home again and someone's cleaning up your house and getting rid of most of your belongings.
Or let's say you die and your computer gets stripped by your executor in the midst of cleaning up your leftovers.
Either way, or some other way, someone or something is wiping your computer.
Do you have anything in Dropbox that you'd rather have kept? Like the genealogy files you've put in there and/or photographs and/or files you've linked online and want left there?
If you've been backing up your Dropbox contents to an external hard-drive regularly, and left some instructions on where to send the hard-drive, that's got you covered for that part. Although more than one hard-drive is good because they can fail.
When I recently sent 120GB of video to one of my sisters, I told her to immediately copy them onto her computer and then back them up again to a newer external. Honestly, people don't take this stuff seriously enough. Another sister lost ALL her photographs a few years ago because she had no backup for them. But I digress ...
If you're linking files from Dropbox to various places online the external backup won't help you at all.
You know, of course, if you delete something from Dropbox on your computer, in 30 days it's also going to be deleted from your Dropbox account online. Sync means sync.
If someone strips your computer, everything you've got in Dropbox is going to be gone too.
If you want to keep files in Dropbox forever, (however long 'forever' might be) regardless of what happens to your computer, there's an option called Selective Sync.
If I click on the Dropbox icon in my system tray, then click on the little gear icon in the upper right corner and then click on Preferences and the Account tab, I come to Selective Sync. If I click on that I come to a list of my Dropbox contents.
The folders that I've unchecked will stay in the cloud on Dropbox as long as my account exists but they will not show up on my computer. That means if my computer is stripped, the files are still where I want them to be.
There's a slight change of habit required here. IF I want to add a file to one of the unchecked folders, I will have to add it online. I can't put it in Dropbox on my computer because the folder's not there.
This is a simple matter of dragging and dropping the file from my computer into the right folder online, first opening my Dropbox account from this small icon.
If the folder isn't already there, I create one. And then drop the file in.
As I drag the file across, the folder will light up in green to show me that Dropbox sees it coming.
Of course, I also keep a backup of these files on my computer. In the meantime.