Is Google Drive a backup?
Not in any meaningful sense. Google Drive is a sync service: it mirrors your working folder, so deletions, overwrites, and ransomware damage sync to the cloud copy too. Version history exists but is limited (typically 30 days, 100 versions per file). For real protection, pair it with a true backup service or at least understand exactly what it does not do.
Google Drive does its actual job well: your files follow you across devices, sharing works, and the free 15 GB is generous. The trouble starts when "my files are in the cloud" quietly becomes "my files are backed up" in someone’s head, because the two statements describe different guarantees.
Walk through the failure cases. You delete a folder and empty the trash: gone after 30 days, everywhere. A file gets corrupted and the corruption syncs: older versions exist, but only for 30 days and 100 revisions, and recovering hundreds of files version-by-version is its own punishment. Ransomware encrypts your synced folder: Drive uploads the encrypted versions promptly, as designed. Your Google account gets locked or compromised: access to everything vanishes at once, which is also a single point of failure no version history fixes.
The pragmatic setup for Google-centric lives: keep using Drive and Google Photos for daily convenience, then add one layer underneath: a true backup of your computer (Backblaze, IDrive) that includes your local Drive folder, or at minimum Google Takeout exports on a calendar reminder plus a second copy of irreplaceables (photos, documents) at a different provider, ideally an encrypted one like Sync.com or Proton Drive. Convenience and recovery are different products; Google sells you the first and only gestures at the second.