I see a use-case here in backing up data.

The data can be archived and then compressed using .tar.xz or something like that, and then split into smaller chunks, which can each be uploaded to some server individually which then embeds them into a large central storage rack (or data center).

Everyone will always need to back up data, and according to what you said, more storage = more security, so this is a perfect arrangement - users get their data backed up, and the chain becomes secure against 51% attackers (and ransomware).

In case a user wants to encrypt the data so that it's only visible to themselves, their client can simply derive an AES key from a password, similar to how Bitcoin Core does it, and use that to encrypt/decrypt each of the chunks. Losing the key is not a problem because as long as you still have access to the data, you can just make a new backup copy.