Have you seen the prices for Google Drive et al? The NAS setup you describe (which I wouldn't consider worth the money for that little space) is what, 12GB with 1 parity drive?

Google One for 10TB is 274,99€/mo (at least in my country) so you'd make the entire nas price and subscription cost within a few months, let alone years.

There just aren't compelling public cloud for large sizes (My NAS is 30TB capacity and I'm using 18 right now) and even if you go the more complex loops with like S3 and whatnot you still get billed more than it's worth. Public cloud is meant for public files, there's a lot of costs you're paying for stuff you don't need like being fast to access from everywhere.