I think that anyone with actual experience of operating thousands of physical disks in datacenters would challenge this assumption.
Don't get me wrong, I buy the actual numbers regarding hardware costs, but in addition to that presenting the rest as basically a one man show in terms of maintenance hours is the point where I'm very sceptical.
we also use cloudflare extensively for everything that isn't the core heap dataset, the convenience of buckets is totally worth it for most day-to-day usage.
the heap is really just the main pretraining corpus and nothing else.
The biggest hurdle is getting a mgmt system in place to alert you when something goes wrong - especially at this size. Grafana, Loki, monit, etc are all good tools to leverage that provide quick fault identification.