the real problem is that processing the data with FHE on someone else's computer is tens of thousands of times less efficient than doing it yourself, unencrypte

the real problem is that processing the data with FHE on someone else's computer is tens of thousands of times less efficient than doing it yourself, unencrypted, on your own computer, so there's no real benefit from offloading the computation. except if you're mixing data sources. for instance, say that I have a sweet Snapchat filter that I don't want to let off my servers. and you want to use my filter, but you don't want me to see your face in plaintext. in that case you can send me your encrypted photo, I run it through my filter, and send the results to you for you to decrypt. its only real use case is that type of split data custody.