I have such a NAS for 8 years, (and a smaller netgear one from maybe 16 years ago), and have yet such a disk fail. But you can get unlucky, buying a supposedly new but "refurbished" item via amazon or the seagate store (so I hear), or have the equivalent of the "death star" HDDs, which had a ridicilously high burnout rate (we measured something like > 10% of the drives failed every week across a fairly large deployhment in the field - major bummer.
If you use such consumer drives, I strongly suggest to make occasional offsite backups of large mostly static files (movies for most people I guess), and frequent backups of more volatile directories to an offsite place, maybe encrypted in the cloud.