Most people never backup their computer until they have a disc crash.
Remember too, that lots of computers that are actually used to hold data for a business, home or charity that were bought within the last three years, have more than enough power for any task. So there is little reason to change especially as these machines will run the latest versions of most common software. Only those used exclusively for music and games tend to get changed regularly.
So it is often the case, that a sizeable business is run on one or more computers that are more than a couple of years old.
So beware! As many believe that hard discs don't have a lifetime of much greater than three or four years.
It is for this and many other reasons that you should always backup your computer.
If you don't you won't have any problems unless your computer fails. But then you will have major ones!
And do it regularly every day!