Google cloud has deleted user's data by mistake in the past.
In any case, you should always make backups regardless of where your data is stored. At home, your biggest threat is loss of data, probably through hardware malfunction, house fires or similar.
In the cloud your biggest threat is not loss of data but loss of access to data. Different scenarios but identical outcomes.
Backup solves both scenarios, RAID doesn't solve any of them, but sadly, many people think "oh but I've got RAID6 so surely I cannot lose data".
Of course, syncing a NAS between yourself and a friend or family member's home may be the better solution over cloud options.