Conspiracy theories are everywhere.

From a comment on an Amazon review of a frigging thermostat, for crying out loud, by a user with the name “Live Free or Die”:

But with all this talk about security no one seems to have mentioned the issue that the Nest sends all your electricity usage to their servers.

Giving away your energy consumption numbers only enables third parties like the power company and the government to start drafting/implementing rules around energy usage per household. Stay away from this! (Don’t believe me? Search for “PG&E and smart-meters”)