Not necessarily. For example, I'm pretty sure Dropbox isn't making money by mining my content -- they don't even show me ads. They make money by offering premium plans with more storage. Dropbox could offer a client-side encrypted version of their service without changing their economics -- and there are other companies that already do this. MEGA and Spideroak both do this, with free plans offering 50 GB and 2GB, respectively. Lastpass is another example.