Actually, it costs them a lot of money, my pihole is blocking 2000 requests per day from my nest thermostat. Multiply that for the millions of units they sold and you have a small scale "Perpetual DDoS Attack" to their servers. I don't know why a thermostat needs to call home that often, if it's to checking the outside temperature it could do it just twice a day, or just avoid it altogether when it's off (8 months per year in my case)

But yes, I will never buy this shit again from them, and the next must have the option to be controlled without internet. It doesn't make sense to send a message to a server in another continent to activate a device that's located in the same room I'm sitting in