It is proper Netiquette to back up important files. Don't get caught without a copy.
Saving copies of files makes starting over easy in the event of data loss. Data loss happens for various reasons. Data loss can occur because a hard drive dies, liquid spills on an electronic device, fire, flood, and tornado, just to name a few things that can ruin a computer.
Many people use the internet to backup their data on a regular schedule. There are popular free and paid online data backup services. Software can be installed for automatic cloud backup free from many popular services. Automatic backups are a setting that can be enabled for iOS and Android mobile.
Backup important files because data can easily be lost by accident, virus, or hack.