Is hard drive failure eminent? files disappearing from iMac

Files have started disappearing from my 94 year old uncle's iMac ( 5 yr old, running Sierra).

(Uncle is no longer as Mac savvy as he previously was.)

At first I thought he accidentally tossed two key folders or accidentally emptied other folders so that their content is now loose on his hard drive.This happened two or three weeks ago. I ran Disk Utility and other utilities, no problems noted but missing folder and its contents are gone.

This past week more items disappeared. ALL The items on his desktop are gone (aliases for the most part (and he does not have several desktops, does not use Mission Control) AND the folder I had re created to replace one of he key folders that disappeared three weeks ago also is again gone.Luckily many of the internal documents and sub folders are in his iCloud Drive but stuff is missing from his hard drive.

The iMac boots and is responsive, no unusual noises,

There was very little in his computer's Trash

I don't see how Uncle could lose so many items.

Could the disappearing files and folders be indication of hard drive failure? Or warping of read/write heads causing drive damage and lost data?

I don't want to send uncle to purchase a new drive or Mac unnecessarily but would I be prudent urging him to do so ASAP?