If you've got anything on a computer it needs to be backed up. There's a lot of accidents waiting to happen from disk problems (and SSD disks can lose data worse than hard drives) through human error to viruses and even theft. There's a lot of options and for the record I'm going to list what I do.

Every night I use Apple's Time Machine to backup the files on the iMac to an external hard drive. Time Machine keeps old versions of files which has been very useful in the past. It's not necessarily perfect - I have seen it confused by files changing path not timestamp.

I use Google Drive to keep daily cloud backups of important files and directories.

I also hold some files on an external drive (to reduce storage used on the main drive) and synch that to Microsoft's OneDrive.

Photographs and other Apple documents are synched to the cloud using Apple's iCloud storage.