What I always tell clients:

Me: Okay, so here are all of your original files. Please store and/or save them on your hard drive or in some place where you can access them easily. Make sure that you do that because I delete the files after a week from job completion.

Client: Right! Thank you!

What almost always happens after a week (or a month, or a year):

Client: Hey, buddy! Do you mind sending me the files again? We kinda lost some of them and we need them pronto!

Me: …

And that’s why I actually save all of the files on my backup hard drive all the time.

Source: Clients from Hell