I keep asking for one cryptocurrency based application or service with a lot of users that is not directly related to cryptocurrency itself and that is not illegal.

I keep getting nil. I keep searching independently and getting nil.

The closest I've found is the Sia storage network but it's hard to set up and not competitive with cloud storage. If I want privacy I can just encrypt locally before using S3, Backblaze, etc. If I want redundancy I can use two cloud storage services in parallel.