This is a great question. A good rule to remember, at least as a default, is that anyone who has physical access to your computer can access your data. The question then becomes how much effort do they have to put in to accessing it. Technically speaking, we can access your data (just as any other cloud provider can). Aside from the technical, it is in our best interest to not do this. There are no benefits to us in doing so, only negatives.