How, realistically, are we going to stop them from spying?
That is a good question. I very much doubt that we can argue with them to get them to stop. The leadership of the spy organizations are both very certain that they are right, and it is to their personal advantage to continue down the current road. Political leaders tend to either agree, not care or be open for manipulation (with terrorism and pedos giving the spies leverage). Agreement comes from that insidious group of political leaders who want to control their own population. Technology can give some protection against spying, but the large governments have huge budgets, and can apply pressure to get back doors. The only alternative left (as I see it) is to create pressure on the political system from the outside, however, that requires getting a lot of people to care enough to get off their asses and demand change. Alas, it does not look like that is happening.