I cannot speak for the big companies, but for private cloud storage, I suggest to go the route for self-hosting, all the tools are available in 2022: ZFS for reliability, Proxmox for separation of concerns, Opnsense/pfsense for access control, Nextcloud for convenience (if you need such file sync at all). Add a photovoltaic plant and your electricity bill will be _Ok_ (you should do this anyway).

I have a 40 TB ZFS Z2 Pool consisting of 6x 8TB drives, and a 16TB offsite pool that is booted for backup snapshots weekly. You'll have to replace the 6 drives running 24/7 approximately every 5 years. If a drive costs $200.00, that will be $1200.00 per 5 years, or $20.00 per month. Add about $400.00 (with PV) to $800.00 (without) for electricity per year ($30.00/$60.00 monthly) and $7.00 monthly for UPS batteries. For these $57.00, you will get a full virtualization feature set under your control, not only a 30TB ingress data sink.

With Amazon Glacier, the cheapest "data sink" cloud storage, 30TB would equal $123.00 monthly (or $30.00 with S3 Glacier Deep Archive), with quite a few feature caveats.