The premium plan from Google has 2 TB and costs about the same annually as the electricity for the NAS that the GP comment suggested for comparison (at 100% usage). So at the same ONGOING cost (not even counting initial investment), the NAS has 8 times more storage. 16 times if you assume it will be mostly idle. Except if you want high availability with RAID, then you're back to 8 times. And haven't yet thought about backups.
All this assuming that you even need that much storage, which most people definitely do not.
Google cloud has deleted user's data by mistake in the past.
I'm willing to bet that far more data has been lost to people serving their own data, than Google has lost data.
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".
Having experienced batches of faulty HDDs in a home NAS, you can definitely lose data with RAID6/ZFS-2 even.
Of course, syncing a NAS between yourself and a friend or family member's home may be the better solution over cloud options.