This strategy of selling at such low prices that are likely less than cost only works until it doesn’t. It’s like a gym that sells $20/month memberships and then goes out of business after a few years. The revenue model is dependent on people buying memberships, recognizing revenue, and then having a significant portion of that membership not use or hardly ever use the facility. Once the bottom falls out on that business model and new members stop coming in, the business falls into a death spiral of sorts, which SF appears desperate to get out of.
Looking at SEAS and CF business models, both are largely sustainable in that the prices being charged cover the costs of running the business without gimmicky cross subsidizing. Basically it’s the $50-60 month gym model that can sustain itself long term.