A loose connection could cause you to lose data.
If you lose the connection when the computer is writing to the hard drive then there is a chance that the drive file structure could be corrupted and the drive may become unreadable.
Replacement cables are cheap, certainly cheaper than a few hours work for a professional photographer.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
For the sake of your own health and sanity, if your data is important to you, keep a second copy on another storage (a backup)
