I'm no storage expert, but it seems like the reputable cloud storage providers tend to have lousy pricing. A quick search turns up the quote "I’d be surprised if their S3 gross margin were lower than 70%".
I think people use S3 not because their prices are great, but because they're not comfortable trusting some no-name company that offers better pricing. Protocols like Filecoin aim to remove the need for trust, by having untrusted storage providers prove that they're storing some data.
These anonymous storage providers almost certain aren't following convention best practices in terms of RAID, UPSs etc, so a single copy of the data has a greater likelihood of being lost, but we can compensate for that with extra redundancy.
I think people use S3 not because their prices are great, but because they're not comfortable trusting some no-name company that offers better pricing. Protocols like Filecoin aim to remove the need for trust, by having untrusted storage providers prove that they're storing some data.
These anonymous storage providers almost certain aren't following convention best practices in terms of RAID, UPSs etc, so a single copy of the data has a greater likelihood of being lost, but we can compensate for that with extra redundancy.