That's why its being open source is relevant. Paranoid folks like us set up a private network locally or on any number of our own physically secure servers.
It's also an interesting question:
How comfortable do we feel relying upon the "principle of least authority" long-term in a mixed-trust environment? i.e., a p2p-style Tahoe-LAFS grid, or deploying it privately using a commercial vendor like Amazon S3 (either directly or through Dropbox for free), on our own servers, and everything in between.
You might not trust companies from certain countries with your data, and you shouldn't be forced to in order to store it* in the cloud*.
[0] https://en.wikipedia.org/wiki/Principle_of_Least_Authority