You heard of Edward Snowden that's for sure.
Somehow you woke up and want out of the cloud.
One thing you might still miss: the Dropbox server was kind of a clearing instance and you didn't need to have at least two computers online to get things going. That's true, but think of using a Raspberry Pi as the "always on" repository. Works just fine and is even faster.
You might even consider using Syncthing instead of BtSync, because it is open source.