While Google Drive (and it's competitors such as Dropbox and OneDrive) do a great job of making files available on multiple devices, they aren't true backup tools that retain files indefinitely. Google is remedying that with the release of Google Backup and Sync for macOS and Windows.
Google Drive and Google Photos are being replaced with Backup and Sync. Instead of limiting file sync and backup to one folder like Drive, Backup and Sync let's you choose which folders are sent to your Google Drive.
Unlike Drive, which synchronised all changes, Backup and Sync lets you choose what happens when you delete files, allowing you to delete files from a device while keeping them in Drive.
You can read more at Google's blog where you'll download links for the Windows and macOS clients.