But... the billions and billions of customers
Nest made people realize that thermostats don't have to be complex. Anyone can replace the cryptic commercial programmable unit in your home with a thermostat that's one tap away from doing what you want. That begs the question of why anyone needs a device as complicated as a Nest. $20 buys a digital thermostat with up/down/heat/cool/fan/off buttons and a simple setup menu. Better still, the $20 thermostat isn't chatting about your activities over the Internet or bricking itself on software upgrades.