You can also just be keeping large video files around (some people only use a phone so those 258 gigs are all they have). Another issue is having your gallery

You can also just be keeping large video files around (some people only use a phone so those 258 gigs are all they have). Another issue is having your gallery sync to google's cloud for example. Then you only have at most 10 gigs and you get warnings that you'll stop receiving your email unless you clean up or pay. The cloud sync issue I've seen multiple times on phones of relatives.