Earlier quoted context omitted.
How many companies sustain entire businesses just based on selling thermostats? If Nest captured the entire market and sold $225 thermostats, that's less than a $300 million a year revenue in an entire year. That doesn't take into account wholesale prices. What does the net income look like?
Being sustainable does not mean being a unicorn. As said the issue is that the aim always to exit. And also that they approach this as a Silicon Valley tech company and not as a "standard" company... So spending goes out of hands and it's a billion dollars or nothing.
Personally, at this point I refuse to use products and services made by startups unless I have no other choice. Seeking "an exit" is startup code word for "we don't give a flying fuck about customers and our products; it's only a vehicle to get us rich".