An interesting article from a company providing statistics on 25,000 hard drives in use over the past 5 years. They found 5% of all drives failed within one year. 20% failed within 4 years and the rate of failure appeared to increase each year after 4 years by 10%. These drives were in use 24 hours a day / 7 days a week unlike a typical home user but still good info to have in regards to backing up your data.
It is a good idea to have multiple copies of your important files saved to multiple devices. One trick is having a portable USB hard drive that is only connected to your computer while backing up files (daily, weekly or monthly). Cloud storage and other “off-site” storage is also advantageous to insure your data is protected.