A woman who can't be bothered to backup her epic important things 
Part of the problem, people used to backup to a tape drive and take the tapes off-line; these days most everyone is backing up to hard-drives or storage that stays connected. So, the virus encrypts your backups.
So far the reports are that the virus encrypts only drives that have a letter assigned, so if you backup to a UNC share or a partition that have no letter assigned, your backups should be safe, for now. But there is nothing that prevents a next version of the virus to get to those.
As such, not only do you need to backup, you also need to devise a way of taking the backups offline.
Hear hear. With the current sizes of your typical photos and videos - you would need a helluva lot of blank writable media. But what about external HDD's? There's your offline backup, for a really cheap GB/$ ratio. Me myself would not care if someone encrypted my info, I can always make new. There are some important personal archives with message archives, some photos, tons of bookmarks, creative stuff like lyrics and art, but I'm tempted to delete that stuff myself on a daily basis.
And in the end - paying 300$ for a valuable lesson is not as bad as having your laptop completely stolen or something.